Reconfigurable intelligent surface aided positioning

ABSTRACT

Disclosed are techniques for wireless communication, and specifically for reconfigurable intelligent surface (RIS)-aided positioning. In some aspects, a base station (BS) may transmit, to a user equipment (UE), a first positioning reference signal (PRS). The BS may transmit, to RIS configured to reflect a received signal towards the UE, a second PRS. The BS may receive, from the UE, a downlink reference signal time difference (RSTD) measurement for the first PRS and the second PRS.

CROSS-REFERENCE TO RELATED APPLICATION

The present application for patent claims priority to Greek PatentApplication No. 20200100736, entitled “RECONFIGURABLE INTELLIGENTSURFACE AIDED POSITIONING” filed Dec. 17, 2020, and International PatentApplication No. PCT/US2021/072919, entitled “RECONFIGURABLE INTELLIGENTSURFACE AIDED POSITIONING,” filed Dec. 14, 2021, both of which areassigned to the assignee hereof and are expressly incorporated herein byreference in their entirety.

BACKGROUND OF THE DISCLOSURE 1. Field of the Disclosure

Aspects of the disclosure relate generally to wireless communications.

2. Description of the Related Art

Wireless communication systems have developed through variousgenerations, including a first-generation analog wireless phone service(1G), a second-generation (2G) digital wireless phone service (includinginterim 2.5G and 2.75G networks), a third-generation (3G) high speeddata, Internet-capable wireless service and a fourth-generation (4G)service (e.g., Long Term Evolution (LTE) or WiMax). There are presentlymany different types of wireless communication systems in use, includingcellular and personal communications service (PCS) systems. Examples ofknown cellular systems include the cellular analog advanced mobile phonesystem (AMPS), and digital cellular systems based on code divisionmultiple access (CDMA), frequency division multiple access (FDMA), timedivision multiple access (TDMA), the Global System for Mobilecommunications (GSM), etc.

A fifth generation (5G) wireless standard, referred to as New Radio(NR), calls for higher data transfer speeds, greater numbers ofconnections, and better coverage, among other improvements. The 5Gstandard, according to the Next Generation Mobile Networks Alliance, isdesigned to provide data rates of several tens of megabits per second toeach of tens of thousands of users, with 1 gigabit per second to tens ofworkers on an office floor. Several hundreds of thousands ofsimultaneous connections should be supported in order to support largesensor deployments. Consequently, the spectral efficiency of 5G mobilecommunications should be significantly enhanced compared to the current4G standard. Furthermore, signaling efficiencies should be enhanced andlatency should be substantially reduced compared to current standards.

SUMMARY

The following presents a simplified summary relating to one or moreaspects disclosed herein. Thus, the following summary should not beconsidered an extensive overview relating to all contemplated aspects,nor should the following summary be considered to identify key orcritical elements relating to all contemplated aspects or to delineatethe scope associated with any particular aspect. Accordingly, thefollowing summary has the sole purpose to present certain conceptsrelating to one or more aspects relating to the mechanisms disclosedherein in a simplified form to precede the detailed descriptionpresented below.

In some aspects, a method of wireless communication performed by a basestation includes transmitting, to a user equipment (UE), a firstpositioning reference signal (PRS), transmitting, to a reconfigurableintelligent surface (RIS) configured to reflect a received signal to theUE, a second PRS, and receiving, from the UE, a downlink referencesignal time difference (RSTD) measurement for the first PRS and thesecond PRS.

In some aspects, a method of wireless communication performed by a UEincludes receiving, from a base station (BS), a first PRS, receiving,from a RIS configured to reflect a received signal to the UE, a secondPRS, and transmitting, to the BS, a downlink RSTD measurement for thefirst PRS and the second PRS.

In some aspects, a method of wireless communication performed by a RISincludes receiving configuration information for configuring the RIS toreflect a received signal, receiving a PRS or a sounding referencesignal (SRS), and reflecting the PRS or SRS according to theconfiguration information.

In some aspects, a BS includes one or more memories, one or moreprocessors, communicatively coupled to the one or more memories,configured to transmit, to a UE, a first PRS, transmit, to a RISconfigured to reflect a received signal to the UE, a second PRS, andreceive, from the UE, a downlink RSTD measurement for the first PRS andthe second PRS.

In some aspects, a UE includes one or more memories, one or moreprocessors, communicatively coupled to the one or more memories,configured to receive, from a BS, a first PRS, receive, from a RISconfigured to reflect a received signal to the UE, a second PRS, andtransmit, to the BS, a downlink RSTD measurement for the first PRS andthe second PRS.

In some aspects, a RIS includes one or more memories, one or moreprocessors, communicatively coupled to the one or more memories,configured to receive configuration information for configuring the RISto reflect a received signal, receive a PRS or a SRS, and reflect thePRS or SRS according to the configuration information.

In some aspects, a BS includes means for transmitting, to a UE, a firstPRS, means for transmitting, to a RIS configured to reflect a receivedsignal to the UE, a second PRS, and means for receiving, from the UE, adownlink RSTD measurement for the first PRS and the second PRS.

In some aspects, a UE includes means for receiving, from a BS, a firstPRS, means for receiving, from a RIS configured to reflect a receivedsignal to the UE, a second PRS, and means for transmitting, to the BS, adownlink RSTD measurement for the first PRS and the second PRS.

In some aspects, a RIS includes means for receiving configurationinformation for configuring the RIS to reflect a received signal, meansfor receiving a PRS or a SRS, and means for reflecting the PRS or SRSaccording to the configuration information.

In some aspects, a non-transitory computer-readable medium storing a setof instructions, the set of instructions comprising one or moreinstructions that, when executed by one or more processors of a BS,cause the base station to transmit, to a UE, a first PRS, transmit, to aRIS configured to reflect a received signal to the UE, a second PRS, andreceive, from the UE, a downlink RSTD measurement for the first PRS andthe second PRS.

In some aspects, a non-transitory computer-readable medium storing a setof instructions, the set of instructions comprising one or moreinstructions that, when executed by one or more processors of a UE,cause the UE to receive, from a BS, a first PRS, receive, from a RISconfigured to reflect a received signal to the UE, a second PRS, andtransmit, to the BS, a downlink RSTD measurement for the first PRS andthe second PRS.

In some aspects, a non-transitory computer-readable medium storing a setof instructions, the set of instructions comprising one or moreinstructions that, when executed by one or more processors of a RIS,cause the RIS to receive configuration information for configuring theRIS to reflect a received signal, receive a PRS or a SRS, and reflectthe PRS or SRS according to the configuration information.

Other objects and advantages associated with the aspects disclosedherein will be apparent to those skilled in the art based on theaccompanying drawings and detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are presented to aid in the description ofvarious aspects of the disclosure and are provided solely forillustration of the aspects and not limitation thereof.

FIG. 1 illustrates an example wireless communications system, accordingto aspects of the disclosure.

FIGS. 2A and 2B illustrate example wireless network structures,according to aspects of the disclosure.

FIGS. 3A to 3C are simplified block diagrams of several sample aspectsof components that may be employed in a user equipment (UE), a basestation, and a network entity, respectively, and configured to supportcommunications as taught herein.

FIGS. 4A to 4D are diagrams illustrating example frame structures andchannels within the frame structures, according to aspects of thedisclosure.

FIG. 5 is a diagram illustrating an example base station incommunication with an example UE, according to aspects of thedisclosure.

FIG. 6 illustrates an example of conventional DL time difference ofarrival (TDoA) based positioning.

FIG. 7 illustrates a system for wireless communication using areconfigurable intelligent surface (RIS) according to some aspects.

FIG. 8 illustrates a system for RIS-aided RSTD measurement according tosome aspects.

FIGS. 9 to 11 are flowcharts of example processes associated withRIS-aided positioning according to some aspects.

DETAILED DESCRIPTION

Aspects of the disclosure are provided in the following description andrelated drawings directed to various examples provided for illustrationpurposes. Alternate aspects may be devised without departing from thescope of the disclosure. Additionally, well-known elements of thedisclosure will not be described in detail or will be omitted so as notto obscure the relevant details of the disclosure.

The words “exemplary” and/or “example” are used herein to mean “servingas an example, instance, or illustration.” Any aspect described hereinas “exemplary” and/or “example” is not necessarily to be construed aspreferred or advantageous over other aspects. Likewise, the term“aspects of the disclosure” does not require that all aspects of thedisclosure include the discussed feature, advantage or mode ofoperation.

Those of skill in the art will appreciate that the information andsignals described below may be represented using any of a variety ofdifferent technologies and techniques. For example, data, instructions,commands, information, signals, bits, symbols, and chips that may bereferenced throughout the description below may be represented byvoltages, currents, electromagnetic waves, magnetic fields or particles,optical fields or particles, or any combination thereof, depending inpart on the particular application, in part on the desired design, inpart on the corresponding technology, etc.

Further, many aspects are described in terms of sequences of actions tobe performed by, for example, elements of a computing device. It will berecognized that various actions described herein can be performed byspecific circuits (e.g., application specific integrated circuits(ASICs)), by program instructions being executed by one or moreprocessors, or by a combination of both. Additionally, the sequence(s)of actions described herein can be considered to be embodied entirelywithin any form of non-transitory computer-readable storage mediumhaving stored therein a corresponding set of computer instructions that,upon execution, would cause or instruct an associated processor of adevice to perform the functionality described herein. Thus, the variousaspects of the disclosure may be embodied in a number of differentforms, all of which have been contemplated to be within the scope of theclaimed subject matter. In addition, for each of the aspects describedherein, the corresponding form of any such aspects may be describedherein as, for example, “logic configured to” perform the describedaction.

As used herein, the terms “user equipment” (UE) and “base station” arenot intended to be specific or otherwise limited to any particular radioaccess technology (RAT), unless otherwise noted. In general, a UE may beany wireless communication device (e.g., a mobile phone, router, tabletcomputer, laptop computer, consumer asset tracking device, wearable(e.g., smartwatch, glasses, augmented reality (AR)/virtual reality (VR)headset, etc.), vehicle (e.g., automobile, motorcycle, bicycle, etc.),Internet of Things (IoT) device, etc.) used by a user to communicateover a wireless communications network. A UE may be mobile or may (e.g.,at certain times) be stationary, and may communicate with a radio accessnetwork (RAN). As used herein, the term “UE” may be referred tointerchangeably as an “access terminal” or “AT,” a “client device,” a“wireless device,” a “subscriber device,” a “subscriber terminal,” a“subscriber station,” a “user terminal” or “UT,” a “mobile device,” a“mobile terminal,” a “mobile station,” or variations thereof. Generally,UEs can communicate with a core network via a RAN, and through the corenetwork the UEs can be connected with external networks such as theInternet and with other UEs. Of course, other mechanisms of connectingto the core network and/or the Internet are also possible for the UEs,such as over wired access networks, wireless local area network (WLAN)networks (e.g., based on the Institute of Electrical and ElectronicsEngineers (IEEE) 802.11 specification, etc.) and so on.

A base station may operate according to one of several RATs incommunication with UEs depending on the network in which it is deployed,and may be alternatively referred to as an access point (AP), a networknode, a NodeB, an evolved NodeB (eNB), a next generation eNB (ng-eNB), aNew Radio (NR) Node B (also referred to as a gNB or gNodeB), etc. A basestation may be used primarily to support wireless access by UEs,including supporting data, voice, and/or signaling connections for thesupported UEs. In some systems a base station may provide purely edgenode signaling functions while in other systems it may provideadditional control and/or network management functions. A communicationlink through which UEs can send signals to a base station is called anuplink (UL) channel (e.g., a reverse traffic channel, a reverse controlchannel, an access channel, etc.). A communication link through whichthe base station can send signals to UEs is called a downlink (DL) orforward link channel (e.g., a paging channel, a control channel, abroadcast channel, a forward traffic channel, etc.). As used herein theterm traffic channel (TCH) can refer to either an uplink/reverse ordownlink/forward traffic channel.

The term “base station” may refer to a single physicaltransmission-reception point (TRP) or to multiple physical TRPs that mayor may not be co-located. For example, where the term “base station”refers to a single physical TRP, the physical TRP may be an antenna ofthe base station corresponding to a cell (or several cell sectors) ofthe base station. Where the term “base station” refers to multipleco-located physical TRPs, the physical TRPs may be an array of antennas(e.g., as in a multiple-input multiple-output (MIMO) system or where thebase station employs beamforming) of the base station. Where the term“base station” refers to multiple non-co-located physical TRPs, thephysical TRPs may be a distributed antenna system (DAS) (a network ofspatially separated antennas connected to a common source via atransport medium) or a remote radio head (RRH) (a remote base stationconnected to a serving base station). Alternatively, the non-co-locatedphysical TRPs may be the serving base station receiving the measurementreport from the UE and a neighbor base station whose reference RFsignals the UE is measuring. Because a TRP is the point from which abase station transmits and receives wireless signals, as used herein,references to transmission from or reception at a base station are to beunderstood as referring to a particular TRP of the base station.

In some implementations that support positioning of UEs, a base stationmay not support wireless access by UEs (e.g., may not support data,voice, and/or signaling connections for UEs), but may instead transmitreference signals to UEs to be measured by the UEs, and/or may receiveand measure signals transmitted by the UEs. Such a base station may bereferred to as a positioning beacon (e.g., when transmitting signals toUEs) and/or as a location measurement unit (e.g., when receiving andmeasuring signals from UEs).

An “RF signal” comprises an electromagnetic wave of a given frequencythat transports information through the space between a transmitter anda receiver. As used herein, a transmitter may transmit a single “RFsignal” or multiple “RF signals” to a receiver. However, the receivermay receive multiple “RF signals” corresponding to each transmitted RFsignal due to the propagation characteristics of RF signals throughmultipath channels. The same transmitted RF signal on different pathsbetween the transmitter and receiver may be referred to as a “multipath”RF signal.

FIG. 1 illustrates an example wireless communications system 100. Thewireless communications system 100 (which may also be referred to as awireless wide area network (WWAN)) may include various base stations 102and various UEs 104. The base stations 102 may include macro cell basestations (high power cellular base stations) and/or small cell basestations (low power cellular base stations). In an aspect, the macrocell base station may include eNBs and/or ng-eNBs where the wirelesscommunications system 100 corresponds to an LTE network, or gNBs wherethe wireless communications system 100 corresponds to a NR network, or acombination of both, and the small cell base stations may includefemtocells, picocells, microcells, etc.

The base stations 102 may collectively form a RAN and interface with acore network 170 (e.g., an evolved packet core (EPC) or a 5G core (5GC))through backhaul links 122, and through the core network 170 to one ormore location servers 172 (which may be part of core network 170 or maybe external to core network 170). In addition to other functions, thebase stations 102 may perform functions that relate to one or more oftransferring user data, radio channel ciphering and deciphering,integrity protection, header compression, mobility control functions(e.g., handover, dual connectivity), inter-cell interferencecoordination, connection setup and release, load balancing, distributionfor non-access stratum (NAS) messages, NAS node selection,synchronization, RAN sharing, multimedia broadcast multicast service(MBMS), subscriber and equipment trace, RAN information management(RIM), paging, positioning, and delivery of warning messages. The basestations 102 may communicate with each other directly or indirectly(e.g., through the EPC/5GC) over backhaul links 134, which may be wiredor wireless.

The base stations 102 may wirelessly communicate with the UEs 104. Eachof the base stations 102 may provide communication coverage for arespective geographic coverage area 110. In an aspect, one or more cellsmay be supported by a base station 102 in each coverage area 110. A“cell” is a logical communication entity used for communication with abase station (e.g., over some frequency resource, referred to as acarrier frequency, component carrier, carrier, band, or the like), andmay be associated with an identifier (e.g., a physical cell identifier(PCI), a virtual cell identifier (VCI), a cell global identifier (CGI))for distinguishing cells operating via the same or a different carrierfrequency. In some cases, different cells may be configured according todifferent protocol types (e.g., machine-type communication (MTC),narrowband IoT (NB-IoT), enhanced mobile broadband (eMBB), or others)that may provide access for different types of UEs.

Because a cell is supported by a specific base station, the term “cell”may refer to either or both of the logical communication entity and thebase station that supports it, depending on the context. In some cases,the term “cell” may also refer to a geographic coverage area of a basestation (e.g., a sector), insofar as a carrier frequency can be detectedand used for communication within some portion of geographic coverageareas 110.

While neighboring macro cell base station 102 geographic coverage areas110 may partially overlap (e.g., in a handover region), some of thegeographic coverage areas 110 may be substantially overlapped by alarger geographic coverage area 110. For example, a small cell basestation 102′ may have a coverage area 110′ that substantially overlapswith the coverage area 110 of one or more macro cell base stations 102.A network that includes both small cell and macro cell base stations maybe known as a heterogeneous network. A heterogeneous network may alsoinclude home eNBs (HeNBs), which may provide service to a restrictedgroup known as a closed subscriber group (CSG).

The communication links 120 between the base stations 102 and the UEs104 may include uplink (also referred to as reverse link) transmissionsfrom a UE 104 to a base station 102 and/or downlink (also referred to asforward link) transmissions from a base station 102 to a UE 104. Thecommunication links 120 may use MIMO antenna technology, includingspatial multiplexing, beamforming, and/or transmit diversity. Thecommunication links 120 may be through one or more carrier frequencies.Allocation of carriers may be asymmetric with respect to downlink anduplink (e.g., more or less carriers may be allocated for downlink thanfor uplink).

The wireless communications system 100 may further include a wirelesslocal area network (WLAN) access point (AP) 150 in communication withWLAN stations (STAs) 152 via communication links 154 in an unlicensedfrequency spectrum (e.g., 5 GHz). When communicating in an unlicensedfrequency spectrum, the WLAN STAs 152 and/or the WLAN AP 150 may performa clear channel assessment (CCA) or listen before talk (LBT) procedureprior to communicating in order to determine whether the channel isavailable.

The small cell base station 102′ may operate in a licensed and/or anunlicensed frequency spectrum. When operating in an unlicensed frequencyspectrum, the small cell base station 102′ may employ LTE or NRtechnology and use the same 5 GHz unlicensed frequency spectrum as usedby the WLAN AP 150. The small cell base station 102′, employing LTE/5Gin an unlicensed frequency spectrum, may boost coverage to and/orincrease capacity of the access network. NR in unlicensed spectrum maybe referred to as NR-U. LTE in an unlicensed spectrum may be referred toas LTE-U, licensed assisted access (LAA), or MulteFire.

The wireless communications system 100 may further include a millimeterwave (mmW) base station 180 that may operate in mmW frequencies and/ornear mmW frequencies in communication with a UE 182. Extremely highfrequency (EHF) is part of the RF in the electromagnetic spectrum. EHFhas a range of 30 GHz to 300 GHz and a wavelength between 1 millimeterand 10 millimeters. Radio waves in this band may be referred to as amillimeter wave. Near mmW may extend down to a frequency of 3 GHz with awavelength of 100 millimeters. The super high frequency (SHF) bandextends between 3 GHz and 30 GHz, also referred to as centimeter wave.Communications using the mmW/near mmW radio frequency band have highpath loss and a relatively short range. The mmW base station 180 and theUE 182 may utilize beamforming (transmit and/or receive) over a mmWcommunication link 184 to compensate for the extremely high path lossand short range. Further, it will be appreciated that in alternativeconfigurations, one or more base stations 102 may also transmit usingmmW or near mmW and beamforming. Accordingly, it will be appreciatedthat the foregoing illustrations are merely examples and should not beconstrued to limit the various aspects disclosed herein.

Transmit beamforming is a technique for focusing an RF signal in aspecific direction. Traditionally, when a network node (e.g., a basestation) broadcasts an RF signal, it broadcasts the signal in alldirections (omni-directionally). With transmit beamforming, the networknode determines where a given target device (e.g., a UE) is located(relative to the transmitting network node) and projects a strongerdownlink RF signal in that specific direction, thereby providing afaster (in terms of data rate) and stronger RF signal for the receivingdevice(s). To change the directionality of the RF signal whentransmitting, a network node can control the phase and relativeamplitude of the RF signal at each of the one or more transmitters thatare broadcasting the RF signal. For example, a network node may use anarray of antennas (referred to as a “phased array” or an “antennaarray”) that creates a beam of RF waves that can be “steered” to pointin different directions, without actually moving the antennas.Specifically, the RF current from the transmitter is fed to theindividual antennas with the correct phase relationship so that theradio waves from the separate antennas add together to increase theradiation in a desired direction, while cancelling to suppress radiationin undesired directions.

Transmit beams may be quasi-co-located, meaning that they appear to thereceiver (e.g., a UE) as having the same parameters, regardless ofwhether or not the transmitting antennas of the network node themselvesare physically co-located. In NR, there are four types ofquasi-co-location (QCL) relations. Specifically, a QCL relation of agiven type means that certain parameters about a target reference RFsignal on a target beam can be derived from information about a sourcereference RF signal on a source beam. If the source reference RF signalis QCL Type A, the receiver can use the source reference RF signal toestimate the Doppler shift, Doppler spread, average delay, and delayspread of a target reference RF signal transmitted on the same channel.If the source reference RF signal is QCL Type B, the receiver can usethe source reference RF signal to estimate the Doppler shift and Dopplerspread of a target reference RF signal transmitted on the same channel.If the source reference RF signal is QCL Type C, the receiver can usethe source reference RF signal to estimate the Doppler shift and averagedelay of a target reference RF signal transmitted on the same channel.If the source reference RF signal is QCL Type D, the receiver can usethe source reference RF signal to estimate the spatial receive parameterof a target reference RF signal transmitted on the same channel.

In receive beamforming, the receiver uses a receive beam to amplify RFsignals detected on a given channel. For example, the receiver canincrease the gain setting and/or adjust the phase setting of an array ofantennas in a particular direction to amplify (e.g., to increase thegain level of) the RF signals received from that direction. Thus, when areceiver is said to beamform in a certain direction, it means the beamgain in that direction is high relative to the beam gain along otherdirections, or the beam gain in that direction is the highest comparedto the beam gain in that direction of all other receive beams availableto the receiver. This results in a stronger received signal strength(e.g., reference signal received power (RSRP), reference signal receivedquality (RSRQ), signal-to-interference-plus-noise ratio (SINR), etc.) ofthe RF signals received from that direction.

Receive beams may be spatially related. A spatial relation means thatparameters for a transmit beam for a second reference signal can bederived from information about a receive beam for a first referencesignal. For example, a UE may use a particular receive beam to receiveone or more reference downlink reference signals (e.g., positioningreference signals (PRS), tracking reference signals (TRS), phasetracking reference signal (PTRS), cell-specific reference signals (CRS),channel state information reference signals (CSI-RS), primarysynchronization signals (PSS), secondary synchronization signals (SSS),synchronization signal blocks (SSBs), etc.) from a base station. The UEcan then form a transmit beam for sending one or more uplink referencesignals (e.g., uplink positioning reference signals (UL-PRS), soundingreference signal (SRS), demodulation reference signals (DMRS), PTRS,etc.) to that base station based on the parameters of the receive beam.

Note that a “downlink” beam may be either a transmit beam or a receivebeam, depending on the entity forming it. For example, if a base stationis forming the downlink beam to transmit a reference signal to a UE, thedownlink beam is a transmit beam. If the UE is forming the downlinkbeam, however, it is a receive beam to receive the downlink referencesignal. Similarly, an “uplink” beam may be either a transmit beam or areceive beam, depending on the entity forming it. For example, if a basestation is forming the uplink beam, it is an uplink receive beam, and ifa UE is forming the uplink beam, it is an uplink transmit beam.

In 5G, the frequency spectrum in which wireless nodes (e.g., basestations 102/180, UEs 104/182) operate is divided into multiplefrequency ranges, FR1 (from 450 to 6000 MHz), FR2 (from 24250 to 52600MHz), FR3 (above 52600 MHz), and FR4 (between FR1 and FR2). In amulti-carrier system, such as 5G, one of the carrier frequencies isreferred to as the “primary carrier” or “anchor carrier” or “primaryserving cell” or “PCell,” and the remaining carrier frequencies arereferred to as “secondary carriers” or “secondary serving cells” or“SCells.” In carrier aggregation, the anchor carrier is the carrieroperating on the primary frequency (e.g., FR1) utilized by a UE 104/182and the cell in which the UE 104/182 either performs the initial radioresource control (RRC) connection establishment procedure or initiatesthe RRC connection re-establishment procedure. The primary carriercarries all common and UE-specific control channels, and may be acarrier in a licensed frequency (however, this is not always the case).A secondary carrier is a carrier operating on a second frequency (e.g.,FR2) that may be configured once the RRC connection is establishedbetween the UE 104 and the anchor carrier and that may be used toprovide additional radio resources. In some cases, the secondary carriermay be a carrier in an unlicensed frequency. The secondary carrier maycontain only necessary signaling information and signals, for example,those that are UE-specific may not be present in the secondary carrier,since both primary uplink and downlink carriers are typicallyUE-specific. This means that different UEs 104/182 in a cell may havedifferent downlink primary carriers. The same is true for the uplinkprimary carriers. The network is able to change the primary carrier ofany UE 104/182 at any time. This is done, for example, to balance theload on different carriers. Because a “serving cell” (whether a PCell oran SCell) corresponds to a carrier frequency/component carrier overwhich some base station is communicating, the term “cell,” “servingcell,” “component carrier,” “carrier frequency,” and the like can beused interchangeably.

For example, still referring to FIG. 1 , one of the frequencies utilizedby the macro cell base stations 102 may be an anchor carrier (or“PCell”) and other frequencies utilized by the macro cell base stations102 and/or the mmW base station 180 may be secondary carriers(“SCells”). The simultaneous transmission and/or reception of multiplecarriers enables the UE 104/182 to significantly increase its datatransmission and/or reception rates. For example, two 20 MHz aggregatedcarriers in a multi-carrier system would theoretically lead to atwo-fold increase in data rate (i.e., 40 MHz), compared to that attainedby a single 20 MHz carrier.

The wireless communications system 100 may further include a UE 164 thatmay communicate with a macro cell base station 102 over a communicationlink 120 and/or the mmW base station 180 over a mmW communication link184. For example, the macro cell base station 102 may support a PCelland one or more SCells for the UE 164 and the mmW base station 180 maysupport one or more SCells for the UE 164.

In the example of FIG. 1 , one or more Earth orbiting satellitepositioning system (SPS) space vehicles (SVs) 112 (e.g., satellites) maybe used as an independent source of location information for any of theillustrated UEs (shown in FIG. 1 as a single UE 104 for simplicity). AUE 104 may include one or more dedicated SPS receivers specificallydesigned to receive signals 124 for deriving geo location informationfrom the SVs 112. An SPS typically includes a system of transmitters(e.g., SVs 112) positioned to enable receivers (e.g., UEs 104) todetermine their location on or above the Earth based, at least in part,on signals received from the transmitters. Such a transmitter typicallytransmits a signal marked with a repeating pseudo-random noise (PN) codeof a set number of chips. While typically located in SVs 112,transmitters may sometimes be located on ground-based control stations,base stations 102, and/or other UEs 104.

The use of SPS signals can be augmented by various satellite-basedaugmentation systems (SBAS) that may be associated with or otherwiseenabled for use with one or more global and/or regional navigationsatellite systems. For example an SBAS may include an augmentationsystem(s) that provides integrity information, differential corrections,etc., such as the Wide Area Augmentation System (WAAS), the EuropeanGeostationary Navigation Overlay Service (EGNOS), the Multi-functionalSatellite Augmentation System (MSAS), the Global Positioning System(GPS) Aided Geo Augmented Navigation or GPS and Geo Augmented Navigationsystem (GAGAN), and/or the like. Thus, as used herein, an SPS mayinclude any combination of one or more global and/or regional navigationsatellite systems and/or augmentation systems, and SPS signals mayinclude SPS, SPS-like, and/or other signals associated with such one ormore SPS.

The wireless communications system 100 may further include one or moreUEs, such as UE 190, that connects indirectly to one or morecommunication networks via one or more device-to-device (D2D)peer-to-peer (P2P) links (referred to as “sidelinks”). In the example ofFIG. 1 , UE 190 has a D2D P2P link 192 with one of the UEs 104 connectedto one of the base stations 102 (e.g., through which UE 190 mayindirectly obtain cellular connectivity) and a D2D P2P link 194 withWLAN STA 152 connected to the WLAN AP 150 (through which UE 190 mayindirectly obtain WLAN-based Internet connectivity). In an example, theD2D P2P links 192 and 194 may be supported with any well-known D2D RAT,such as LTE Direct (LTE-D), WiFi Direct (WiFi-D), Bluetooth®, and so on.

FIG. 2A illustrates an example wireless network structure 200. Forexample, a 5GC 210 (also referred to as a Next Generation Core (NGC))can be viewed functionally as control plane functions 214 (e.g., UEregistration, authentication, network access, gateway selection, etc.)and user plane functions 212, (e.g., UE gateway function, access to datanetworks, IP routing, etc.) which operate cooperatively to form the corenetwork. User plane interface (NG-U) 213 and control plane interface(NG-C) 215 connect the gNB 222 to the 5GC 210 and specifically to thecontrol plane functions 214 and user plane functions 212. In anadditional configuration, an ng-eNB 224 may also be connected to the 5GC210 via NG-C 215 to the control plane functions 214 and NG-U 213 to userplane functions 212. Further, ng-eNB 224 may directly communicate withgNB 222 via a backhaul connection 223. In some configurations, the NewRAN 220 may only have one or more gNBs 222, while other configurationsinclude one or more of both ng-eNBs 224 and gNBs 222. Either gNB 222 orng-eNB 224 may communicate with UEs 204 (e.g., any of the UEs depictedin FIG. 1 ). Another optional aspect may include location server 230,which may be in communication with the 5GC 210 to provide locationassistance for UEs 204. The location server 230 can be implemented as aplurality of separate servers (e.g., physically separate servers,different software modules on a single server, different softwaremodules spread across multiple physical servers, etc.), or alternatelymay each correspond to a single server. The location server 230 can beconfigured to support one or more location services for UEs 204 that canconnect to the location server 230 via the core network, 5GC 210, and/orvia the Internet (not illustrated).

Further, the location server 230 may be integrated into a component ofthe core network, or alternatively may be external to the core network.

FIG. 2B illustrates another example wireless network structure 250. Forexample, a 5GC 260 can be viewed functionally as control planefunctions, provided by an access and mobility management function (AMF)264, and user plane functions, provided by a user plane function (UPF)262, which operate cooperatively to form the core network (i.e., 5GC260). User plane interface 263 and control plane interface 265 connectthe ng-eNB 224 to the 5GC 260 and specifically to UPF 262 and AMF 264,respectively. In an additional configuration, a gNB 222 may also beconnected to the 5GC 260 via control plane interface 265 to AMF 264 anduser plane interface 263 to UPF 262. Further, ng-eNB 224 may directlycommunicate with gNB 222 via the backhaul connection 223, with orwithout gNB direct connectivity to the 5GC 260. In some configurations,the New RAN 220 may only have one or more gNBs 222, while otherconfigurations include one or more of both ng-eNBs 224 and gNBs 222.Either gNB 222 or ng-eNB 224 may communicate with UEs 204 (e.g., any ofthe UEs depicted in FIG. 1 ). The base stations of the New RAN 220communicate with the AMF 264 over the N2 interface and with the UPF 262over the N3 interface.

The functions of the AMF 264 include registration management, connectionmanagement, reachability management, mobility management, lawfulinterception, transport for session management (SM) messages between theUE 204 and a session management function (SMF) 266, transparent proxyservices for routing SM messages, access authentication and accessauthorization, transport for short message service (SMS) messagesbetween the UE 204 and the short message service function (SMSF) (notshown), and security anchor functionality (SEAF). The AMF 264 alsointeracts with an authentication server function (AUSF) (not shown) andthe UE 204, and receives the intermediate key that was established as aresult of the UE 204 authentication process. In the case ofauthentication based on a UMTS (universal mobile telecommunicationssystem) subscriber identity module (USIM), the AMF 264 retrieves thesecurity material from the AUSF. The functions of the AMF 264 alsoinclude security context management (SCM). The SCM receives a key fromthe SEAF that it uses to derive access-network specific keys. Thefunctionality of the AMF 264 also includes location services managementfor regulatory services, transport for location services messagesbetween the UE 204 and a location management function (LMF) 270 (whichacts as a location server 230), transport for location services messagesbetween the New RAN 220 and the LMF 270, evolved packet system (EPS)bearer identifier allocation for interworking with the EPS, and UE 204mobility event notification. In addition, the AMF 264 also supportsfunctionalities for non-3GPP (Third Generation Partnership Project)access networks.

Functions of the UPF 262 include acting as an anchor point forintra-/inter-RAT mobility (when applicable), acting as an externalprotocol data unit (PDU) session point of interconnect to a data network(not shown), providing packet routing and forwarding, packet inspection,user plane policy rule enforcement (e.g., gating, redirection, trafficsteering), lawful interception (user plane collection), traffic usagereporting, quality of service (QoS) handling for the user plane (e.g.,uplink/downlink rate enforcement, reflective QoS marking in thedownlink), uplink traffic verification (service data flow (SDF) to QoSflow mapping), transport level packet marking in the uplink anddownlink, downlink packet buffering and downlink data notificationtriggering, and sending and forwarding of one or more “end markers” tothe source RAN node. The UPF 262 may also support transfer of locationservices messages over a user plane between the UE 204 and a locationserver, such as a secure user plane location (SUPL) location platform(SLP) 272.

The functions of the SMF 266 include session management, UE Internetprotocol (IP) address allocation and management, selection and controlof user plane functions, configuration of traffic steering at the UPF262 to route traffic to the proper destination, control of part ofpolicy enforcement and QoS, and downlink data notification. Theinterface over which the SMF 266 communicates with the AMF 264 isreferred to as the N11 interface.

Another optional aspect may include an LMF 270, which may be incommunication with the 5GC 260 to provide location assistance for UEs204. The LMF 270 can be implemented as a plurality of separate servers(e.g., physically separate servers, different software modules on asingle server, different software modules spread across multiplephysical servers, etc.), or alternately may each correspond to a singleserver. The LMF 270 can be configured to support one or more locationservices for UEs 204 that can connect to the LMF 270 via the corenetwork, 5GC 260, and/or via the Internet (not illustrated). The SLP 272may support similar functions to the LMF 270, but whereas the LMF 270may communicate with the AMF 264, New RAN 220, and UEs 204 over acontrol plane (e.g., using interfaces and protocols intended to conveysignaling messages and not voice or data), the SLP 272 may communicatewith UEs 204 and external clients (not shown in FIG. 2B) over a userplane (e.g., using protocols intended to carry voice and/or data likethe transmission control protocol (TCP) and/or IP).

FIGS. 3A, 3B, and 3C illustrate several example components (representedby corresponding blocks) that may be incorporated into a UE 302 (whichmay correspond to any of the UEs described herein), a base station 304(which may correspond to any of the base stations described herein), anda network entity 306 (which may correspond to or embody any of thenetwork functions described herein, including the location server 230and the LMF 270) to support the file transmission operations as taughtherein. It will be appreciated that these components may be implementedin different types of apparatuses in different implementations (e.g., inan ASIC, in a system-on-chip (SoC), etc.). The illustrated componentsmay also be incorporated into other apparatuses in a communicationsystem. For example, other apparatuses in a system may includecomponents similar to those described to provide similar functionality.Also, a given apparatus may contain one or more of the components. Forexample, an apparatus may include multiple transceiver components thatenable the apparatus to operate on multiple carriers and/or communicatevia different technologies.

The UE 302 and the base station 304 each include wireless wide areanetwork (WWAN) transceiver 310 and 350, respectively, providing meansfor communicating (e.g., means for transmitting, means for receiving,means for measuring, means for tuning, means for refraining fromtransmitting, etc.) via one or more wireless communication networks (notshown), such as an NR network, an LTE network, a GSM network, and/or thelike. The WWAN transceivers 310 and 350 may be connected to one or moreantennas 316 and 356, respectively, for communicating with other networknodes, such as other UEs, access points, base stations (e.g., eNBs,gNBs), etc., via at least one designated RAT (e.g., NR, LTE, GSM, etc.)over a wireless communication medium of interest (e.g., some set oftime/frequency resources in a particular frequency spectrum). The WWANtransceivers 310 and 350 may be variously configured for transmittingand encoding signals 318 and 358 (e.g., messages, indications,information, and so on), respectively, and, conversely, for receivingand decoding signals 318 and 358 (e.g., messages, indications,information, pilots, and so on), respectively, in accordance with thedesignated RAT. Specifically, the WWAN transceivers 310 and 350 includeone or more transmitters 314 and 354, respectively, for transmitting andencoding signals 318 and 358, respectively, and one or more receivers312 and 352, respectively, for receiving and decoding signals 318 and358, respectively.

The UE 302 and the base station 304 also include, at least in somecases, wireless local area network (WLAN) transceivers 320 and 360,respectively. The WLAN transceivers 320 and 360 may be connected to oneor more antennas 326 and 366, respectively, and provide means forcommunicating (e.g., means for transmitting, means for receiving, meansfor measuring, means for tuning, means for refraining from transmitting,etc.) with other network nodes, such as other UEs, access points, basestations, etc., via at least one designated RAT (e.g., WiFi, LTE-D,Bluetooth®, etc.) over a wireless communication medium of interest. TheWLAN transceivers 320 and 360 may be variously configured fortransmitting and encoding signals 328 and 368 (e.g., messages,indications, information, and so on), respectively, and, conversely, forreceiving and decoding signals 328 and 368 (e.g., messages, indications,information, pilots, and so on), respectively, in accordance with thedesignated RAT. Specifically, the WLAN transceivers 320 and 360 includeone or more transmitters 324 and 364, respectively, for transmitting andencoding signals 328 and 368, respectively, and one or more receivers322 and 362, respectively, for receiving and decoding signals 328 and368, respectively.

Transceiver circuitry including at least one transmitter and at leastone receiver may comprise an integrated device (e.g., embodied as atransmitter circuit and a receiver circuit of a single communicationdevice) in some implementations, may comprise a separate transmitterdevice and a separate receiver device in some implementations, or may beembodied in other ways in other implementations. In an aspect, atransmitter may include or be coupled to a plurality of antennas (e.g.,antennas 316, 326, 356, 366), such as an antenna array, that permits therespective apparatus to perform transmit “beamforming,” as describedherein. Similarly, a receiver may include or be coupled to a pluralityof antennas (e.g., antennas 316, 326, 356, 366), such as an antennaarray, that permits the respective apparatus to perform receivebeamforming, as described herein. In an aspect, the transmitter andreceiver may share the same plurality of antennas (e.g., antennas 316,326, 356, 366), such that the respective apparatus can only receive ortransmit at a given time, not both at the same time. A wirelesscommunication device (e.g., one or both of the transceivers 310 and 320and/or 350 and 360) of the UE 302 and/or the base station 304 may alsocomprise a network listen module (NLM) or the like for performingvarious measurements.

The UE 302 and the base station 304 also include, at least in somecases, satellite positioning systems (SPS) receivers 330 and 370. TheSPS receivers 330 and 370 may be connected to one or more antennas 336and 376, respectively, and may provide means for receiving and/ormeasuring SPS signals 338 and 378, respectively, such as globalpositioning system (GPS) signals, global navigation satellite system(GLONASS) signals, Galileo signals, Beidou signals, Indian RegionalNavigation Satellite System (NAVIC), Quasi-Zenith Satellite System(QZSS), etc. The SPS receivers 330 and 370 may comprise any suitablehardware and/or software for receiving and processing SPS signals 338and 378, respectively. The SPS receivers 330 and 370 request informationand operations as appropriate from the other systems, and performscalculations necessary to determine positions of the UE 302 and the basestation 304 using measurements obtained by any suitable SPS algorithm.

The base station 304 and the network entity 306 each include at leastone network interfaces 380 and 390, respectively, providing means forcommunicating (e.g., means for transmitting, means for receiving, etc.)with other network entities. For example, the network interfaces 380 and390 (e.g., one or more network access ports) may be configured tocommunicate with one or more network entities via a wire-based orwireless backhaul connection. In some aspects, the network interfaces380 and 390 may be implemented as transceivers configured to supportwire-based or wireless signal communication. This communication mayinvolve, for example, sending and receiving messages, parameters, and/orother types of information.

The UE 302, the base station 304, and the network entity 306 alsoinclude other components that may be used in conjunction with theoperations as disclosed herein. The UE 302 includes processor circuitryimplementing a processing system 332 for providing functionalityrelating to, for example, wireless positioning, and for providing otherprocessing functionality. The base station 304 includes a processingsystem 384 for providing functionality relating to, for example,wireless positioning as disclosed herein, and for providing otherprocessing functionality. The network entity 306 includes a processingsystem 394 for providing functionality relating to, for example,wireless positioning as disclosed herein, and for providing otherprocessing functionality. The processing systems 332, 384, and 394 maytherefore provide means for processing, such as means for determining,means for calculating, means for receiving, means for transmitting,means for indicating, etc. In an aspect, the processing systems 332,384, and 394 may include, for example, one or more general purposeprocessors, multi-core processors, ASICs, digital signal processors(DSPs), field programmable gate arrays (FPGA), or other programmablelogic devices or processing circuitry.

The UE 302, the base station 304, and the network entity 306 includememory circuitry implementing memory components 340, 386, and 396 (e.g.,each including a memory device and which may be referred to asmemories), respectively, for maintaining information (e.g., informationindicative of reserved resources, thresholds, parameters, and so on).The memory components 340, 386, and 396 may therefore provide means forstoring, means for retrieving, means for maintaining, etc. In somecases, the UE 302, the base station 304, and the network entity 306 mayinclude positioning modules 342, 388, and 398, respectively. Thepositioning modules 342, 388, and 398 may be hardware circuits that arepart of or coupled to the processing systems 332, 384, and 394,respectively, that, when executed, cause the UE 302, the base station304, and the network entity 306 to perform the functionality describedherein. In other aspects, the positioning modules 342, 388, and 398 maybe external to the processing systems 332, 384, and 394 (e.g., part of amodem processing system, integrated with another processing system,etc.). Alternatively, the positioning modules 342, 388, and 398 may bememory modules stored in the memory components 340, 386, and 396,respectively, that, when executed by the processing systems 332, 384,and 394 (or a modem processing system, another processing system, etc.),cause the UE 302, the base station 304, and the network entity 306 toperform the functionality described herein. FIG. 3A illustrates possiblelocations of the positioning module 342, which may be part of the WWANtransceiver 310, the memory component 340, the processing system 332, orany combination thereof, or may be a standalone component. FIG. 3Billustrates possible locations of the positioning module 388, which maybe part of the WWAN transceiver 350, the memory component 386, theprocessing system 384, or any combination thereof, or may be astandalone component. FIG. 3C illustrates possible locations of thepositioning module 398, which may be part of the network interface(s)390, the memory component 396, the processing system 394, or anycombination thereof, or may be a standalone component.

The UE 302 may include one or more sensors 344 coupled to the processingsystem 332 to provide means for sensing or detecting movement and/ororientation information that is independent of motion data derived fromsignals received by the WWAN transceiver 310, the WLAN transceiver 320,and/or the SPS receiver 330. By way of example, the sensor(s) 344 mayinclude an accelerometer (e.g., a micro-electrical mechanical systems(MEMS) device), a gyroscope, a geomagnetic sensor (e.g., a compass), analtimeter (e.g., a barometric pressure altimeter), and/or any other typeof movement detection sensor. Moreover, the sensor(s) 344 may include aplurality of different types of devices and combine their outputs inorder to provide motion information. For example, the sensor(s) 344 mayuse a combination of a multi-axis accelerometer and orientation sensorsto provide the ability to compute positions in 2D and/or 3D coordinatesystems.

In addition, the UE 302 includes a user interface 346 providing meansfor providing indications (e.g., audible and/or visual indications) to auser and/or for receiving user input (e.g., upon user actuation of asensing device such a keypad, a touch screen, a microphone, and so on).Although not shown, the base station 304 and the network entity 306 mayalso include user interfaces.

Referring to the processing system 384 in more detail, in the downlink,IP packets from the network entity 306 may be provided to the processingsystem 384. The processing system 384 may implement functionality for anRRC layer, a packet data convergence protocol (PDCP) layer, a radio linkcontrol (RLC) layer, and a medium access control (MAC) layer. Theprocessing system 384 may provide RRC layer functionality associatedwith broadcasting of system information (e.g., master information block(MIB), system information blocks (SIBs)), RRC connection control (e.g.,RRC connection paging, RRC connection establishment, RRC connectionmodification, and RRC connection release), inter-RAT mobility, andmeasurement configuration for UE measurement reporting; PDCP layerfunctionality associated with header compression/decompression, security(ciphering, deciphering, integrity protection, integrity verification),and handover support functions; RLC layer functionality associated withthe transfer of upper layer PDUs, error correction through automaticrepeat request (ARQ), concatenation, segmentation, and reassembly of RLCservice data units (SDUs), re-segmentation of RLC data PDUs, andreordering of RLC data PDUs; and MAC layer functionality associated withmapping between logical channels and transport channels, schedulinginformation reporting, error correction, priority handling, and logicalchannel prioritization.

The transmitter 354 and the receiver 352 may implement Layer-1 (L1)functionality associated with various signal processing functions.Layer-1, which includes a physical (PHY) layer, may include errordetection on the transport channels, forward error correction (FEC)coding/decoding of the transport channels, interleaving, rate matching,mapping onto physical channels, modulation/demodulation of physicalchannels, and MIMO antenna processing. The transmitter 354 handlesmapping to signal constellations based on various modulation schemes(e.g., binary phase-shift keying (BPSK), quadrature phase-shift keying(QPSK), M-phase-shift keying (M-PSK), M-quadrature amplitude modulation(M-QAM)). The coded and modulated symbols may then be split intoparallel streams. Each stream may then be mapped to an orthogonalfrequency division multiplexing (OFDM) subcarrier, multiplexed with areference signal (e.g., pilot) in the time and/or frequency domain, andthen combined together using an inverse fast Fourier transform (IFFT) toproduce a physical channel carrying a time domain OFDM symbol stream.The OFDM symbol stream is spatially precoded to produce multiple spatialstreams. Channel estimates from a channel estimator may be used todetermine the coding and modulation scheme, as well as for spatialprocessing. The channel estimate may be derived from a reference signaland/or channel condition feedback transmitted by the UE 302. Eachspatial stream may then be provided to one or more different antennas356. The transmitter 354 may modulate an RF carrier with a respectivespatial stream for transmission.

At the UE 302, the receiver 312 receives a signal through its respectiveantenna(s) 316. The receiver 312 recovers information modulated onto anRF carrier and provides the information to the processing system 332.The transmitter 314 and the receiver 312 implement Layer-1 functionalityassociated with various signal processing functions. The receiver 312may perform spatial processing on the information to recover any spatialstreams destined for the UE 302. If multiple spatial streams aredestined for the UE 302, they may be combined by the receiver 312 into asingle OFDM symbol stream. The receiver 312 then converts the OFDMsymbol stream from the time-domain to the frequency domain using a fastFourier transform (FFT). The frequency domain signal comprises aseparate OFDM symbol stream for each subcarrier of the OFDM signal. Thesymbols on each subcarrier, and the reference signal, are recovered anddemodulated by determining the most likely signal constellation pointstransmitted by the base station 304. These soft decisions may be basedon channel estimates computed by a channel estimator. The soft decisionsare then decoded and de-interleaved to recover the data and controlsignals that were originally transmitted by the base station 304 on thephysical channel. The data and control signals are then provided to theprocessing system 332, which implements Layer-3 (L3) and Layer-2 (L2)functionality.

In the uplink, the processing system 332 provides demultiplexing betweentransport and logical channels, packet reassembly, deciphering, headerdecompression, and control signal processing to recover IP packets fromthe core network. The processing system 332 is also responsible forerror detection.

Similar to the functionality described in connection with the downlinktransmission by the base station 304, the processing system 332 providesRRC layer functionality associated with system information (e.g., MIB,SIBs) acquisition, RRC connections, and measurement reporting; PDCPlayer functionality associated with header compression/decompression,and security (ciphering, deciphering, integrity protection, integrityverification); RLC layer functionality associated with the transfer ofupper layer PDUs, error correction through ARQ, concatenation,segmentation, and reassembly of RLC SDUs, re-segmentation of RLC dataPDUs, and reordering of RLC data PDUs; and MAC layer functionalityassociated with mapping between logical channels and transport channels,multiplexing of MAC SDUs onto transport blocks (TBs), demultiplexing ofMAC SDUs from TBs, scheduling information reporting, error correctionthrough hybrid automatic repeat request (HARQ), priority handling, andlogical channel prioritization.

Channel estimates derived by the channel estimator from a referencesignal or feedback transmitted by the base station 304 may be used bythe transmitter 314 to select the appropriate coding and modulationschemes, and to facilitate spatial processing. The spatial streamsgenerated by the transmitter 314 may be provided to different antenna(s)316. The transmitter 314 may modulate an RF carrier with a respectivespatial stream for transmission.

The uplink transmission is processed at the base station 304 in a mannersimilar to that described in connection with the receiver function atthe UE 302. The receiver 352 receives a signal through its respectiveantenna(s) 356. The receiver 352 recovers information modulated onto anRF carrier and provides the information to the processing system 384.

In the uplink, the processing system 384 provides demultiplexing betweentransport and logical channels, packet reassembly, deciphering, headerdecompression, control signal processing to recover IP packets from theUE 302. IP packets from the processing system 384 may be provided to thecore network. The processing system 384 is also responsible for errordetection.

For convenience, the UE 302, the base station 304, and/or the networkentity 306 are shown in FIGS. 3A-C as including various components thatmay be configured according to the various examples described herein. Itwill be appreciated, however, that the illustrated blocks may havedifferent functionality in different designs.

The various components of the UE 302, the base station 304, and thenetwork entity 306 may communicate with each other over data buses 334,382, and 392, respectively. The components of FIGS. 3A-C may beimplemented in various ways. In some implementations, the components ofFIGS. 3A-C may be implemented in one or more circuits such as, forexample, one or more processors and/or one or more ASICs (which mayinclude one or more processors). Here, each circuit may use and/orincorporate at least one memory component for storing information orexecutable code used by the circuit to provide this functionality. Forexample, some or all of the functionality represented by blocks 310 to346 may be implemented by processor and memory component(s) of the UE302 (e.g., by execution of appropriate code and/or by appropriateconfiguration of processor components). Similarly, some or all of thefunctionality represented by blocks 350 to 388 may be implemented byprocessor and memory component(s) of the base station 304 (e.g., byexecution of appropriate code and/or by appropriate configuration ofprocessor components). Also, some or all of the functionalityrepresented by blocks 390 to 398 may be implemented by processor andmemory component(s) of the network entity 306 (e.g., by execution ofappropriate code and/or by appropriate configuration of processorcomponents). For simplicity, various operations, acts, and/or functionsare described herein as being performed “by a UE,” “by a base station,”“by a network entity,” etc. However, as will be appreciated, suchoperations, acts, and/or functions may actually be performed by specificcomponents or combinations of components of the UE 302, base station304, network entity 306, etc., such as the processing systems 332, 384,394, the transceivers 310, 320, 350, and 360, the memory components 340,386, and 396, the positioning modules 342, 388, and 398, etc.

Various frame structures may be used to support downlink and uplinktransmissions between network nodes (e.g., base stations and UEs).

FIG. 4A is a diagram 400 illustrating an example of a downlink framestructure, according to aspects of the disclosure.

LTE, and in some cases NR, utilizes OFDM on the downlink andsingle-carrier frequency division multiplexing (SC-FDM) on the uplink.Unlike LTE, however, NR has an option to use OFDM on the uplink as well.OFDM and SC-FDM partition the system bandwidth into multiple (K)orthogonal subcarriers, which are also commonly referred to as tones,bins, etc. Each subcarrier may be modulated with data. In general,modulation symbols are sent in the frequency domain with OFDM and in thetime domain with SC-FDM. The spacing between adjacent subcarriers may befixed, and the total number of subcarriers (K) may be dependent on thesystem bandwidth. For example, the spacing of the subcarriers may be 15kilohertz (kHz) and the minimum resource allocation (resource block) maybe 12 subcarriers (or 180 kHz). Consequently, the nominal FFT size maybe equal to 128, 256, 512, 1024, or 2048 for system bandwidth of 1.25,2.5, 5, 10, or 20 megahertz (MHz), respectively. The system bandwidthmay also be partitioned into subbands. For example, a subband may cover1.08 MHz (i.e., 6 resource blocks), and there may be 1, 2, 4, 8, or 16subbands for system bandwidth of 1.25, 2.5, 5, 10, or 20 MHz,respectively.

LTE supports a single numerology (subcarrier spacing (SCS), symbollength, etc.). In contrast, NR may support multiple numerologies (μ),for example, subcarrier spacings of 15 kHz (μ=0), 30 kHz (μ=1), 60 kHz(μ=2), 120 kHz (μ=3), and 240 kHz (μ=4) or greater may be available. Ineach subcarrier spacing, there are 14 symbols per slot. For 15 kHz SCS(μ=0), there is one slot per subframe, 10 slots per frame, the slotduration is 1 millisecond (ms), the symbol duration is 66.7 microseconds(μs), and the maximum nominal system bandwidth (in MHz) with a 4K FFTsize is 50. For 30 kHz SCS (μ=1), there are two slots per subframe, 20slots per frame, the slot duration is 0.5 ms, the symbol duration is33.3 μs, and the maximum nominal system bandwidth (in MHz) with a 4K FFTsize is 100. For 60 kHz SCS (μ=2), there are four slots per subframe, 40slots per frame, the slot duration is 0.25 ms, the symbol duration is16.7 μs, and the maximum nominal system bandwidth (in MHz) with a 4K FFTsize is 200. For 120 kHz SCS (μ=3), there are eight slots per subframe,80 slots per frame, the slot duration is 0.125 ms, the symbol durationis 8.33 μs, and the maximum nominal system bandwidth (in MHz) with a 4KFFT size is 400. For 240 kHz SCS (μ=4), there are 16 slots per subframe,160 slots per frame, the slot duration is 0.0625 ms, the symbol durationis 4.17 μs, and the maximum nominal system bandwidth (in MHz) with a 4KFFT size is 800.

In the example of FIGS. 4A to 4D, a numerology of 15 kHz is used. Thus,in the time domain, a 10 ms frame is divided into 10 equally sizedsubframes of 1 ms each, and each subframe includes one time slot. InFIGS. 4A to 4D, time is represented horizontally (on the X axis) withtime increasing from left to right, while frequency is representedvertically (on the Y axis) with frequency increasing (or decreasing)from bottom to top.

A resource grid may be used to represent time slots, each time slotincluding one or more time-concurrent resource blocks (RBs) (alsoreferred to as physical RBs (PRBs)) in the frequency domain. Theresource grid is further divided into multiple resource elements (REs).An RE may correspond to one symbol length in the time domain and onesubcarrier in the frequency domain. In the numerology of FIGS. 4A to 4D,for a normal cyclic prefix, an RB may contain 12 consecutive subcarriersin the frequency domain and seven consecutive symbols in the timedomain, for a total of 84 REs. For an extended cyclic prefix, an RB maycontain 12 consecutive subcarriers in the frequency domain and sixconsecutive symbols in the time domain, for a total of 72 REs. Thenumber of bits carried by each RE depends on the modulation scheme.

Some of the REs carry downlink reference (pilot) signals (DL-RS). TheDL-RS may include PRS, TRS, PTRS, CRS, CSI-RS, DMRS, PSS, SSS, SSB, etc.FIG. 4A illustrates example locations of REs carrying PRS (labeled “R”).

A collection of resource elements (REs) that are used for transmissionof PRS is referred to as a “PRS resource.” The collection of resourceelements can span multiple PRBs in the frequency domain and ‘N’ (such as1 or more) consecutive symbol(s) within a slot in the time domain. In agiven OFDM symbol in the time domain, a PRS resource occupiesconsecutive PRBs in the frequency domain.

The transmission of a PRS resource within a given PRB has a particularcomb size (also referred to as the “comb density”). A comb size ‘N’represents the subcarrier spacing (or frequency/tone spacing) withineach symbol of a PRS resource configuration. Specifically, for a combsize ‘N,’ PRS are transmitted in every Nth subcarrier of a symbol of aPRB. For example, for comb-4, for each symbol of the PRS resourceconfiguration, REs corresponding to every fourth subcarrier (such assubcarriers 0, 4, 8) are used to transmit PRS of the PRS resource.Currently, comb sizes of comb-2, comb-4, comb-6, and comb-12 aresupported for DL-PRS. FIG. 4A illustrates an example PRS resourceconfiguration for comb-6 (which spans six symbols). That is, thelocations of the shaded REs (labeled “R”) indicate a comb-6 PRS resourceconfiguration.

Currently, a DL-PRS resource may span 2, 4, 6, or 12 consecutive symbolswithin a slot with a fully frequency-domain staggered pattern. A DL-PRSresource can be configured in any higher layer configured downlink orflexible (FL) symbol of a slot. There may be a constant energy perresource element (EPRE) for all REs of a given DL-PRS resource. Thefollowing are the frequency offsets from symbol to symbol for comb sizes2, 4, 6, and 12 over 2, 4, 6, and 12 symbols. 2-symbol comb-2: {0, 1};4-symbol comb-2: {0, 1, 0, 1}; 6-symbol comb-2: {0, 1, 0, 1, 0, 1};12-symbol comb-2: {0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1}; 4-symbol comb-4:{0, 2, 1, 3}; 12-symbol comb-4: {0, 2, 1, 3, 0, 2, 1, 3, 0, 2, 1, 3};6-symbol comb-6: {0, 3, 1, 4, 2, 5}; 12-symbol comb-6: {0, 3, 1, 4, 2,5, 0, 3, 1, 4, 2, 5}; and 12-symbol comb-12: {0, 6, 3, 9, 1, 7, 4, 10,2, 8, 5, 11}.

A “PRS resource set” is a set of PRS resources used for the transmissionof PRS signals, where each PRS resource has a PRS resource ID. Inaddition, the PRS resources in a PRS resource set are associated withthe same TRP. A PRS resource set is identified by a PRS resource set IDand is associated with a particular TRP (identified by a TRP ID). Inaddition, the PRS resources in a PRS resource set have the sameperiodicity, a common muting pattern configuration, and the samerepetition factor (such as “PRS-ResourceRepetitionFactor”) across slots.The periodicity is the time from the first repetition of the first PRSresource of a first PRS instance to the same first repetition of thesame first PRS resource of the next PRS instance. The periodicity mayhave a length selected from 2{circumflex over ( )}μ*{4, 5, 8, 10, 16,20, 32, 40, 64, 80, 160, 320, 640, 1280, 2560, 5120, 10240} slots, withμ=0, 1, 2, 3. The repetition factor may have a length selected from {1,2, 4, 6, 8, 16, 32} slots.

A PRS resource ID in a PRS resource set is associated with a single beam(or beam ID) transmitted from a single TRP (where a TRP may transmit oneor more beams). That is, each PRS resource of a PRS resource set may betransmitted on a different beam, and as such, a “PRS resource,” orsimply “resource,” also can be referred to as a “beam.” Note that thisdoes not have any implications on whether the TRPs and the beams onwhich PRS are transmitted are known to the UE.

A “PRS instance” or “PRS occasion” is one instance of a periodicallyrepeated time window (such as a group of one or more consecutive slots)where PRS are expected to be transmitted. A PRS occasion also may bereferred to as a “PRS positioning occasion,” a “PRS positioninginstance, a “positioning occasion,” “a positioning instance,” a“positioning repetition,” or simply an “occasion,” an “instance,” or a“repetition.”

A “positioning frequency layer” (also referred to simply as a “frequencylayer”) is a collection of one or more PRS resource sets across one ormore TRPs that have the same values for certain parameters.Specifically, the collection of PRS resource sets has the samesubcarrier spacing and cyclic prefix (CP) type (meaning all numerologiessupported for the PDSCH are also supported for PRS), the same Point A,the same value of the downlink PRS bandwidth, the same start PRB (andcenter frequency), and the same comb-size. The Point A parameter takesthe value of the parameter “ARFCN-ValueNR” (where “ARFCN” stands for“absolute radio-frequency channel number”) and is an identifier/codethat specifies a pair of physical radio channel used for transmissionand reception. The downlink PRS bandwidth may have a granularity of fourPRBs, with a minimum of 24 PRBs and a maximum of 272 PRBs. Currently, upto four frequency layers have been defined, and up to two PRS resourcesets may be configured per TRP per frequency layer.

The concept of a frequency layer is somewhat like the concept ofcomponent carriers and bandwidth parts (BWPs), but different in thatcomponent carriers and BWPs are used by one base station (or a macrocell base station and a small cell base station) to transmit datachannels, while frequency layers are used by several (usually three ormore) base stations to transmit PRS. A UE may indicate the number offrequency layers it can support when it sends the network itspositioning capabilities, such as during an LTE positioning protocol(LPP) session. For example, a UE may indicate whether it can support oneor four positioning frequency layers.

FIG. 4B is a diagram 430 illustrating an example of channels within thedownlink frame structure, according to aspects of the disclosure. FIG.4B illustrates an example of various channels within a downlink slot ofa radio frame. In NR, the channel bandwidth, or system bandwidth, isdivided into multiple BWPs. A BWP is a contiguous set of PRBs selectedfrom a contiguous subset of the common RBs for a given numerology on agiven carrier. Generally, a maximum of four BWPs can be specified in thedownlink and uplink. That is, a UE can be configured with up to fourBWPs on the downlink, and up to four BWPs on the uplink. Only one BWP(uplink or downlink) may be active at a given time, meaning the UE mayonly receive or transmit over one BWP at a time. On the downlink, thebandwidth of each BWP should be equal to or greater than the bandwidthof the SSB, but it may or may not contain the SSB.

Referring to FIG. 4B, a primary synchronization signal (PSS) is used bya UE to determine subframe/symbol timing and a physical layer identity.A secondary synchronization signal (SSS) is used by a UE to determine aphysical layer cell identity group number and radio frame timing. Basedon the physical layer identity and the physical layer cell identitygroup number, the UE can determine a PCI. Based on the PCI, the UE candetermine the locations of the aforementioned DL-RS. The physicalbroadcast channel (PBCH), which carries an MIB, may be logically groupedwith the PSS and SSS to form an SSB (also referred to as an SS/PBCH).The MIB provides a number of RBs in the downlink system bandwidth and asystem frame number (SFN). The physical downlink shared channel (PDSCH)carries user data, broadcast system information not transmitted throughthe PBCH, such as system information blocks (SIBs), and paging messages.

The physical downlink control channel (PDCCH) carries downlink controlinformation (DCI) within one or more control channel elements (CCEs),each CCE including one or more RE group (REG) bundles (which may spanmultiple symbols in the time domain), each REG bundle including one ormore REGs, each REG corresponding to 12 resource elements (one resourceblock) in the frequency domain and one OFDM symbol in the time domain.The set of physical resources used to carry the PDCCH/DCI is referred toin NR as the control resource set (CORESET). In NR, a PDCCH is confinedto a single CORESET and is transmitted with its own DMRS. This enablesUE-specific beamforming for the PDCCH.

In the example of FIG. 4B, there is one CORESET per BWP, and the CORESETspans three symbols (although it may be only one or two symbols) in thetime domain. Unlike LTE control channels, which occupy the entire systembandwidth, in NR, PDCCH channels are localized to a specific region inthe frequency domain (i.e., a CORESET). Thus, the frequency component ofthe PDCCH shown in FIG. 4B is illustrated as less than a single BWP inthe frequency domain. Note that although the illustrated CORESET iscontiguous in the frequency domain, it need not be. In addition, theCORESET may span less than three symbols in the time domain.

The DCI within the PDCCH carries information about uplink resourceallocation (persistent and non-persistent) and descriptions aboutdownlink data transmitted to the UE, referred to as uplink and downlinkgrants, respectively. More specifically, the DCI indicates the resourcesscheduled for the downlink data channel (e.g., PDSCH) and the uplinkdata channel (e.g., PUSCH). Multiple (e.g., up to eight) DCIs can beconfigured in the PDCCH, and these DCIs can have one of multipleformats. For example, there are different DCI formats for uplinkscheduling, for downlink scheduling, for uplink transmit power control(TPC), etc. A PDCCH may be transported by 1, 2, 4, 8, or 16 CCEs inorder to accommodate different DCI payload sizes or coding rates.

FIG. 4C is a diagram 450 illustrating an example of an uplink framestructure, according to aspects of the disclosure. As illustrated inFIG. 4C, some of the REs (labeled “R”) carry DMRS for channel estimationat the receiver (e.g., a base station, another UE, etc.). A UE mayadditionally transmit SRS in, for example, the last symbol of a slot.The SRS may have a comb structure, and a UE may transmit SRS on one ofthe combs. In the example of FIG. 4C, the illustrated SRS is comb-2 overone symbol. The SRS may be used by a base station to obtain the channelstate information (CSI) for each UE. CSI describes how an RF signalpropagates from the UE to the base station and represents the combinedeffect of scattering, fading, and power decay with distance. The systemuses the SRS for resource scheduling, link adaptation, massive MIMO,beam management, etc.

Currently, an SRS resource may span 1, 2, 4, 8, or 12 consecutivesymbols within a slot with a comb size of comb-2, comb-4, or comb-8. Thefollowing are the frequency offsets from symbol to symbol for the SRScomb patterns that are currently supported. 1-symbol comb-2: {0};2-symbol comb-2: {0, 1}; 4-symbol comb-2: {0, 1, 0, 1}; 4-symbol comb-4:{0, 2, 1, 3}; 8-symbol comb-4: {0, 2, 1, 3, 0, 2, 1, 3}; 12-symbolcomb-4: {0, 2, 1, 3, 0, 2, 1, 3, 0, 2, 1, 3}; 4-symbol comb-8: {0, 4, 2,6}; 8-symbol comb-8: {0, 4, 2, 6, 1, 5, 3, 7}; and 12-symbol comb-8: {0,4, 2, 6, 1, 5, 3, 7, 0, 4, 2, 6}.

A collection of resource elements that are used for transmission of SRSis referred to as an “SRS resource,” and may be identified by theparameter “SRS-ResourceId.” The collection of resource elements can spanmultiple PRBs in the frequency domain and N (e.g., one or more)consecutive symbol(s) within a slot in the time domain. In a given OFDMsymbol, an SRS resource occupies consecutive PRBs. An “SRS resource set”is a set of SRS resources used for the transmission of SRS signals, andis identified by an SRS resource set ID (“SRS-ResourceSetId”).

Generally, a UE transmits SRS to enable the receiving base station(either the serving base station or a neighboring base station) tomeasure the channel quality between the UE and the base station.However, SRS also can be used as uplink positioning reference signalsfor uplink positioning procedures, such as UL-TDOA, multi-RTT, DL-AoA,etc.

Several enhancements over the previous definition of SRS have beenproposed for SRS-for-positioning (also referred to as “UL-PRS”), such asa new staggered pattern within an SRS resource (except forsingle-symbol/comb-2), a new comb type for SRS, new sequences for SRS, ahigher number of SRS resource sets per component carrier, and a highernumber of SRS resources per component carrier. In addition, theparameters “SpatialRelationInfo” and “PathLossReference” are to beconfigured based on a downlink reference signal or SSB from aneighboring TRP. Further still, one SRS resource may be transmittedoutside the active BWP, and one SRS resource may span across multiplecomponent carriers. Also, SRS may be configured in RRC connected stateand only transmitted within an active BWP. Further, there may be nofrequency hopping, no repetition factor, a single antenna port, and newlengths for SRS (e.g., 8 and 12 symbols). There also may be open-looppower control and not closed-loop power control, and comb-8 (i.e., anSRS transmitted every eighth subcarrier in the same symbol) may be used.Lastly, the UE may transmit through the same transmit beam from multipleSRS resources for UL-AoA. All of these are features that are additionalto the current SRS framework, which is configured through RRC higherlayer signaling (and potentially triggered or activated through MACcontrol element (CE) or DCI).

FIG. 4D is a diagram 470 illustrating an example of channels within anuplink frame structure, according to aspects of the disclosure. Arandom-access channel (RACH), also referred to as a physicalrandom-access channel (PRACH), may be within one or more slots within aframe based on the PRACH configuration. The PRACH may include sixconsecutive RB pairs within a slot. The PRACH allows the UE to performinitial system access and achieve uplink synchronization. A physicaluplink control channel (PUCCH) may be located on edges of the uplinksystem bandwidth. The PUCCH carries uplink control information (UCI),such as scheduling requests, CSI reports, a channel quality indicator(CQI), a precoding matrix indicator (PMI), a rank indicator (RI), andHARQ ACK/NACK feedback. The physical uplink shared channel (PUSCH)carries data, and may additionally be used to carry a buffer statusreport (BSR), a power headroom report (PHR), and/or UCI.

Other wireless communications technologies may have different framestructures and/or different channels. Note that the terms “positioningreference signal” and “PRS” generally refer to specific referencesignals that are used for positioning in NR and LTE systems. However, asused herein, the terms “positioning reference signal” and “PRS” may alsorefer to any type of reference signal that can be used for positioning,such as but not limited to, PRS as defined in LTE and NR, TRS, PTRS,CRS, CSI-RS, DMRS, PSS, SSS, SSB, SRS, UL-PRS, etc. In addition, theterms “positioning reference signal” and “PRS” may refer to downlink oruplink positioning reference signals, unless otherwise indicated by thecontext. If needed to further distinguish the type of PRS, a downlinkpositioning reference signal may be referred to as a “DL-PRS,” and anuplink positioning reference signal (e.g., an SRS-for-positioning, PTRS)may be referred to as an “UL-PRS.” In addition, for signals that may betransmitted in both the uplink and downlink (e.g., DMRS, PTRS), thesignals may be prepended with “UL” or “DL” to distinguish the direction.For example, “UL-DMRS” may be differentiated from “DL-DMRS.”

FIG. 5 is a diagram 500 illustrating a base station (BS) 502 (which maycorrespond to any of the base stations described herein) incommunication with a UE 504 (which may correspond to any of the UEsdescribed herein). Referring to FIG. 5 , the base station 502 maytransmit a beamformed signal to the UE 504 on one or more transmit beams502 a, 502 b, 502 c, 502 d, 502 e, 502 f, 502 g, 502 h, each having abeam identifier that can be used by the UE 504 to identify therespective beam. Where the base station 502 is beamforming towards theUE 504 with a single array of antennas (e.g., a single TRP/cell), thebase station 502 may perform a “beam sweep” by transmitting first beam502 a, then beam 502 b, and so on until lastly transmitting beam 502 h.Alternatively, the base station 502 may transmit beams 502 a-502 h insome pattern, such as beam 502 a, then beam 502 h, then beam 502 b, thenbeam 502 g, and so on. Where the base station 502 is beamforming towardsthe UE 504 using multiple arrays of antennas (e.g., multipleTRPs/cells), each antenna array may perform a beam sweep of a subset ofthe beams 502 a-502 h. Alternatively, each of beams 502 a-502 h maycorrespond to a single antenna or antenna array.

FIG. 5 further illustrates the paths 506 c, 506 d, 506 e, 506 f, and 506g followed by the beamformed signal transmitted on beams 502 c, 502 d,502 e, 502 f, and 502 g, respectively. Each path 506 c, 506 d, 506 e,506 f, 506 g may correspond to a single “multipath” or, due to thepropagation characteristics of radio frequency (RF) signals through theenvironment, may be comprised of a plurality (a cluster) of“multipaths.” Note that although only the paths for beams 502 c-502 gare shown, this is for simplicity, and the signal transmitted on each ofbeams 502 a-502 h will follow some path. In the example shown, the paths506 c, 506 d, 506 e, and 506 f are straight lines, while path 506 greflects off an obstacle 508 (e.g., a building, vehicle, terrainfeature, etc.).

The UE 504 may receive the beamformed signal from the base station 502on one or more receive beams 504 a, 504 b, 504 c, 504 d. Note that forsimplicity, the beams illustrated in FIG. 5 represent either transmitbeams or receive beams, depending on which of the base station 502 andthe UE 504 is transmitting and which is receiving. Thus, the UE 504 mayalso transmit a beamformed signal to the base station 502 on one or moreof the beams 504 a-504 d, and the base station 502 may receive thebeamformed signal from the UE 504 on one or more of the beams 502 a-502h.

In an aspect, the base station 502 and the UE 504 may perform beamtraining to align the transmit and receive beams of the base station 502and the UE 504. For example, depending on environmental conditions andother factors, the base station 502 and the UE 504 may determine thatthe best transmit and receive beams are 502 d and 504 b, respectively,or beams 502 e and 504 c, respectively. The direction of the besttransmit beam for the base station 502 may or may not be the same as thedirection of the best receive beam, and likewise, the direction of thebest receive beam for the UE 504 may or may not be the same as thedirection of the best transmit beam.

To perform a DL-AoD positioning procedure, the base station 502 maytransmit reference signals (e.g., PRS, CRS, TRS, CSI-RS, PSS, SSS, etc.)to the UE 504 on one or more of beams 502 a-502 h, with each beam havinga different transmit angle. The different transmit angles of the beams502 a-502 h will result in different received signal strengths (e.g.,RSRP, RSRQ, SINR, etc.) at the UE 504. The received signal strength willbe lower for transmit beams 502 a-502 h that are further from the lineof sight (LOS) path 510 between the base station 502 and the UE 504 thanfor transmit beams 502 a-502 h that are closer to the LOS path 510.

In the example of FIG. 5 , if the base station 502 transmits referencesignals to the UE 504 on beams 502 c, 502 d, 502 e, 502 f, and 502 g,then transmit beam 502 e is best aligned with the LOS path 510, whiletransmit beams 502 c, 502 d, 502 f, and 502 g are not. As such, beam 502e is likely to have a higher received signal strength at the UE 504 thanbeams 502 c, 502 d, 502 f, and 502 g. Note that the reference signalstransmitted on some beams (e.g., beams 502 c and/or 502 f) may not reachthe UE 504, or energy reaching the UE 504 from these beams may be so lowthat the energy may not be detectable or at least can be ignored.

The UE 504 can report the received signal strength, and optionally, theassociated measurement quality, of each measured transmit beam 502 c-502g to the base station 502, or alternatively, the identity of thetransmit beam having the highest received signal strength (beam 502 e inthe example of FIG. 5 ). Alternatively or additionally, if the UE 504 isalso engaged in a round-trip-time (RTT) or time-difference of arrival(TDOA) positioning session with at least one base station 502 or aplurality of base stations 502, respectively, the UE 504 can reportreception-to-transmission (Rx-Tx) or reference signal time difference(RSTD) measurements (and optionally the associated measurementqualities), respectively, to the serving base station 502 or otherpositioning entity. In any case, the positioning entity (e.g., the basestation 502, a location server, a third-party client, UE 504, etc.) canestimate the angle from the base station 502 to the UE 504 as the AoD ofthe transmit beam having the highest received signal strength (andstrongest channel impulse response and/or earliest ToA if reported) atthe UE 504, here, transmit beam 502 e.

FIG. 6 illustrates an example of conventional DL time difference ofarrival (TDoA) based positioning. In DL-TDoA, the difference in ToAbetween synchronized cells, e.g., gNB1, gNB2, and gNB3 in FIG. 6 ,provides a distance estimate along hyperbolas. Multiple TDoAmeasurements are used for triangulation, e.g., four or more cells.Network synchronization error among the gNBs is the main obstacle tohigh precision positioning. The potential timing errors τ1, τ2, and τ3create a measurement uncertainty along each hyperbola.

FIG. 7 illustrates a system 700 for wireless communication using areconfigurable intelligent surface (RIS) 702 according to some aspects.An RIS is an artificial structure with engineered electromagnetic (EM)properties, which can collect wireless signals from a transmitter andpassively beamform them towards a desired receiver. An RIS can beconfigured to reflect an impinging wave to a desired direction. In theexample illustrated in FIG. 7 , a first BS 102 a controls the RIS 702but a second BS 102 b does not control the RIS 702. The enhancedfunctionality of the system 700 can provide technical benefits in anumber of scenarios.

For example, in FIG. 7 , the first BS 102 a is attempting to communicatewith a first UE 104 a that is behind an obstacle 704 (e.g., a building,hill, or other obstacle) and thus cannot receive what would otherwisebeen a LOS beam from the first BS 102 a, i.e., transmit beam 2. In thisscenario, the first BS 102 a may instead use transmit beam 1 to direct asignal to the RIS 702, which the first BS 102 a configures to reflectthe incoming transmit beam 1 towards the first UE 104 a and around theobstacle 704. It should be noted that the first BS 102 a may configurethe RIS 702 for the UE's use in UL, e.g., such that the first UE 104 acan bounce an UL signal to the first BS 102 a using the RIS 702 and thusget around the obstacle 704.

In another scenario, the first BS 102 a may be aware that an obstacle,such as obstacle 704 in FIG. 7 , may create a dead zone, e.g., ageographic area in which the signal from BS 102 a is attenuated, makingthe signal difficult to detect by a UE within that dead zone. In thisscenario, the BS 102 a may bounce a signal off of the RIS 702 into thedead zone in order to provide coverage to devices which may be there,including devices about which the BS 102 a is not currently aware.

Yet another scenario in which system 700 provides a technical advantageis one involving a low-tier (e.g., low-power, low-bandwidth,low-antenna-count, low baseband processing capability) UE, such as a “NRlight” or “NR RedCap” UE, which may not have the capability to hear ordetect a PRS transmitted from a non-serving gNB, especially for gNBsthat are far from the UE. Likewise, an SRS measurement by a non-servinggNB of an SRS from a low-tier UE may be poor. The same problems may betrue for UEs that are not low-tier UEs, under certain circumstances. Forwhatever reason, when a UE cannot detect a sufficient number ofpositioning signals from different TRPs, the use of the RIS 702 canprovide one or more additional positioning signals from a single TRP.When multiple positioning signals are provided by the same TRP, theproblem of network synchronization errors between TRPs becomes moot, andthat obstacle to high-precision positioning is avoided. An example ofthis specific scenario is shown in FIG. 8 .

FIG. 8 illustrates a system 800 for RIS-aided RSTD measurement accordingto some aspects. The top portion of FIG. 8 shows the geographicalpositions of the entities involved in an example scenario and the bottomportion of FIG. 8 illustrates the timing of the signal transmissions andreflections in this example scenario.

In FIG. 8 , a serving gNB (SgNB) or other type of serving base stationsends a set of positioning reference signals to a target UE. A first PRS802 is directed towards a first RIS (RIS1), a second PRS 804 is directedtowards a second RIS (RIS2), and a third PRS 806 is directed towards thetarget UE. In the example illustrated in FIG. 8 , RIS1 is closer thanRIS2 is to the UE. Referring now to the bottom portion of FIG. 8 , thethird PRS 806 arrives at the UE first, at time ToA(SgNB). The first PRS802 arrives at RIS1 at time Tprop(SgNBàRIS1), and RIS1 transmits areflected PRS signal 808, which arrives at the UE at time ToA(RIS1). Thesecond PRS 804 arrives at RIS2 at time Tprop(SgNBà RIS2), and RIS2transmits a reflected PRS signal 810, which arrives at the UE at timeToA(RIS2). The UE measures the times of arrival (Rx) of each of PRSsignal 806, PRS signal 808, and PRS signal 810. The UE is provided withthe PRS real time difference (PRTD) between a pair of PRS transmissions.

RSTD is the difference in the time that it takes one reference signal toreach the UE and the time that it takes another reference signal toreach the UE. Thus, RSTD is the difference between the ToA of onereference and the ToA of another reference.

In the example shown in FIG. 8 , the UE can calculate a value for ToA(=Rx−Tx) for each of the third PRS 806, the reflected PRS signal 808,and the reflected PRS signal 810, namely, ToA(SgNB), ToA(RIS1), andToA(RIS2), as well as RSTD values for each pair. For example, the UE maycompute the RSTD between the SgNB and RIS1 using the following equation:

$\begin{matrix}{{{RSTD}\left( {{SgNB},{{RIS}1}} \right)} = {{{ToA}({SgNB})} - {{ToA}\left( {{RIS}1} \right)}}} \\{= {\left( {{{Rx}({SgNB})} - {{Tx}({SgNB})}} \right) -}} \\\left( \left( {{{Rx}\left( {{RIS}1} \right)} - {{Tx}\left( {{RIS}1} \right)}} \right) \right. \\{= {{{Rx}({SgNB})} - {{Rx}\left( {{RIS}1} \right)} -}} \\{{PRTD} + {{Tprop}\left( {{SgNB}à{RIS}1} \right)}}\end{matrix}$

where

-   -   Rx(SgNB) is the time that the UE receives PRS 806,    -   Rx(RIS1) is the time that the UE receives PRS 808,    -   PRTD is the transmission time offset between PRS 806 and PRS        808, and    -   Tprop(SgNBàRIS1) is the time it takes PRS 802 to reach RIS1.

Note that the transmit time for each PRS is not needed. In this example,the equation will calculate the difference between the time that PRS 806takes to get from the SgNB to the UE and the time that PRS 808 takes toget from RIS1 to the UE.

For UE-assisted positioning, the UE may report RSTD without includingPRTD, and the network will calculate the UE's position based on PRTDdata known to the network but not known by the UE. In order for the UEto perform UE-based positioning (as opposed to UE-assisted positioning),however, the computation of RSTD requires knowledge of the value ofPRTD. In some aspects, the value of PRTD is signaled to the UE viaassistance data provided by a location server. In some aspects, the UEmay use the received PRTD value as an “expected RSTD”, which can informthe UE where it should search for a PRS. In some aspects, the UE may beprovided with an “PRTD uncertainty” value which the UE can use to aidits PRS search window selection. In some aspects, Tprop(SgNBaRIS1 may beestimated through radio access technology (RAT) techniques (e.g.,NR-based positioning) or RAT-independent methods (e.g., high precisionPRS or other hybrid positioning methods).

In some aspects, the UE may know the geographic locations of RIS1 andRIS2, in which case the UE may estimate its own position viatriangulation techniques using the values of RSTD for pair of SgNB,RIS1, and RIS2.

In the example illustrated in FIG. 8 , the SgNB may have configured RIS1to reflect the incoming PRS signal 802 in an intended direction, e.g.,via a link 812 between the SgNB and RIS1. In some circumstances, RIS1may not need to be configured for this purpose, e.g., because RIS1 wasalready suitably configured to reflect an incoming PRS signal in theintended direction, because RIS1 is not configurable by the SgNB butprovides a suitable reflected signal anyway, or because RIS1 wasconfigured by an entity other than the SgNB. The same may be true ofRIS2, e.g., via a link 814 between the SgNB and RIS2. The intendeddirection of the reflected signal may be chosen for various reasons,such as to get a signal to a target UE in a known location, to get asignal into a target area (e.g., where the LOS signal from the SgNB isblocked by a known obstacle) whether a target UE is in that area or not,other reasons, or some combination thereof. The SgNB may not know thelocation of a target UE, and may not know whether or not any UEs are inthe target area. The SgNB relies upon the UE to measure the RISreflected signals.

The signal that a RIS receives from a serving base station may beomnidirectional or beamformed, and the reflected beam produced by theRIS may be similarly omnidirectional or beamformed in nature. When a RISreceives a signal from the serving base station, the RIS may produce areflected signal that is wider, narrower, or the same width intransmission profile. For example, the SgNB may transmit a narrowlybeamformed PRS to RIS1, and RIS1 may reflect a more widely dispersedsignal towards the UE, such as in situations where the location of theUE is not exactly known. Likewise, RIS1 may reflect a more focusedsignal towards the target UE, such as where the location of the UE hasbeen estimated with some confidence and a narrower beam would provide abetter signal to noise ratio towards the target UE.

In some aspects, the SgNB may dynamically control the behavior of RISesunder its control during the process of transmitting multiple PRSsignals. In the scenario illustrated in FIG. 8 , for example, the SgNBmay control RIS2 so that it is disabled while the SgNB is transmittingPRS signal 802 towards RIS1, control RIS1 so that it is disabled whilethe SgNB is transmitting PRS signal 804 towards RIS2, and control RIS1and RIS2 so that both are disabled while the SgNB is transmitting PRSsignal 806 directly towards the UE.

In this manner, the SgNB can reduce or eliminate the likelihood that thetarget UE will receive a reflection from a RIS when a reflection is notdesired, e.g., so that PRS signal 806 does not reflect off of RIS1 orRIS2 and reach the target UE. It is noted that the order of transmissionof the PRS signals is illustrative and not limiting: for example, insome aspects, the SgNB may first transmit a PRS towards the target UE,towards RIS2, then towards RIS1, or in any other order. It is also notedthat although FIG. 8 illustrates an example using two RISes, the sameconcepts may be applied for any number of RISes greater than zero.

Because the above described techniques allow positioning to be performedusing only a single SgNB, they are suitable for use by low-tier UEs,since measurement of neighboring cells is not required. Because networksync errors are not an issue for single cell positioning methods such asthose disclosed herein, these methods have the potential to have higheraccuracy than conventional methods that require measurement ofneighboring cells. It is noted that, in some aspects, these techniquesmay also be applied in combination with conventional techniques thatrequire measurement of neighboring cells.

FIG. 9 is a flowchart of an example process 900 associated withRIS-aided positioning according to some aspects. In someimplementations, one or more process blocks of FIG. 9 may be performedby a BS (e.g., BS 102). In some implementations, one or more processblocks of FIG. 9 may be performed by another device or a group ofdevices separate from or including the BS. Additionally, oralternatively, one or more process blocks of FIG. 9 may be performed byone or more components of device 304, such as processing system 384,memory 386, WWAN transceiver 350, WLAN transceiver 360, and/or networkinterface 380.

As shown in FIG. 9 , process 900 may include transmitting, to a UE, afirst PRS (block 910). For example, the BS may transmit, to a UE, afirst PRS, as described above.

As further shown in FIG. 9 , process 900 may include transmitting, to areconfigurable intelligent surface (RIS) configured to reflect areceived signal to the UE, a second PRS (block 920). For example, the BSmay transmit, to a reconfigurable intelligent surface (RIS) configuredto reflect a received signal to the UE, a second PRS, as describedabove.

As further shown in FIG. 9 , process 900 may include receiving, from theUE, a downlink reference signal time difference (RSTD) measurement forthe first PRS and the second PRS (block 930). For example, the BS mayreceive, from the UE, a downlink RSTD measurement for the first PRS andthe second PRS, as described above. In some aspects, the RSTDmeasurement is the difference between the ToA for the first PRS and theToA for the second PRS, which may or may not consider the transmissiontime offset between the first PRS and the second PRS.

Process 900 may include additional implementations, such as any singleimplementation or any combination of implementations described belowand/or in connection with one or more other processes describedelsewhere herein.

In a first implementation, process 900 includes calculating an estimatedposition of the UE based on the RSTD measurements.

In a second implementation, alone or in combination with the firstimplementation, process 900 includes receiving, from the UE, anestimated position of the UE.

In a third implementation, alone or in combination with one or more ofthe first and second implementations, indicating a transmission timeoffset between the first PRS and the second PRS comprises providing thetransmission time offset via explicit signaling, indicating thetransmission time offset based on a PRS mapping, or combinationsthereof.

In a fourth implementation, alone or in combination with one or more ofthe first through third implementations, receiving the downlink RSTDmeasurement for the first PRS and the second PRS comprises receiving areceive time, a time of arrival, or combinations thereof for the firstPRS and the second PRS.

In a fifth implementation, alone or in combination with one or more ofthe first through fourth implementations, prior to transmitting thesecond PRS, configuring the RIS to reflect a received signal to the UE.

In a sixth implementation, alone or in combination with one or more ofthe first through fifth implementations, prior to transmitting the firstPRS, configuring the RIS to not reflect a received signal to the UE.

In a seventh implementation, alone or in combination with one or more ofthe first through sixth implementations, prior to receiving the RSTDmeasurements, indicating, to the UE, a transmission time offset betweenthe first PRS and the second PRS.

Although FIG. 9 shows example blocks of process 900, in someimplementations, process 900 may include additional blocks, fewerblocks, different blocks, or differently arranged blocks than thosedepicted in FIG. 9 . Additionally, or alternatively, two or more of theblocks of process 900 may be performed in parallel.

FIG. 10 is a flowchart of an example process 1000 associated withRIS-aided positioning. In some implementations, one or more processblocks of FIG. 10 may be performed by a user equipment (UE) (e.g., UE104). In some implementations, one or more process blocks of FIG. 10 maybe performed by another device or a group of devices separate from orincluding the UE. Additionally, or alternatively, one or more processblocks of FIG. 10 may be performed by one or more components of device302, such as the processing system 332, memory 340, WWAN transceiver310, WLAN transceiver 320, and/or user interface 346.

As shown in FIG. 10 , process 1000 may include receiving, from a BS, afirst PRS (block 1010). For example, the UE may receive, from a BS, afirst PRS, as described above.

As further shown in FIG. 10 , process 1000 may include receiving, from aRIS configured to reflect a received signal to the UE, a second PRS(block 1020). For example, the UE may receive, from a RIS configured toreflect a received signal to the UE, a second PRS, as described above.

As further shown in FIG. 10 , process 1000 may include transmitting, tothe BS, a downlink RSTD measurement for the first PRS and the second PRS(block 1030). For example, the UE may transmit, to the BS, a downlinkRSTD measurement for the first PRS and the second PRS, as describedabove.

Process 1000 may include additional implementations, such as any singleimplementation or any combination of implementations described belowand/or in connection with one or more other processes describedelsewhere herein.

In a first implementation, process 1000 includes determining atransmission time offset between the first PRS and the second PRS,calculating an estimated position of the UE based on the RSTDmeasurements and the transmission time offset between the first PRS andthe second PRS, and transmitting, to the BS, the estimated position ofthe UE.

In a second implementation, alone or in combination with the firstimplementation, determining the transmission time offset between thefirst PRS and the second PRS comprises receiving the transmission timeoffset via explicit signaling, determining the transmission time offsetbased on a PRS mapping, or combinations thereof.

In a third implementation, alone or in combination with one or more ofthe first and second implementations, transmitting the downlink RSTDmeasurement for the first PRS and the second PRS comprises transmittinga receive time, a time of arrival, or combinations thereof for the firstPRS and the second PRS.

Although FIG. 10 shows example blocks of process 1000, in someimplementations, process 1000 may include additional blocks, fewerblocks, different blocks, or differently arranged blocks than thosedepicted in FIG. 10 . Additionally, or alternatively, two or more of theblocks of process 1000 may be performed in parallel.

FIG. 11 is a flowchart of an example process 1100 associated withRIS-aided positioning. In some implementations, one or more processblocks of FIG. 11 may be performed by a RIS (e.g., RIS 702). In someimplementations, one or more process blocks of FIG. 11 may be performedby another device or a group of devices separate from or including theRIS.

As shown in FIG. 11 , process 1100 may include receiving configurationinformation for configuring the RIS to reflect a received signal (block1110). For example, the RIS may receive configuration information forconfiguring the RIS to reflect a received signal, as described above.

As further shown in FIG. 11 , process 1100 may include receiving, from aBS, a PRS or SRS (block 1120). For example, the RIS may receive, from aBS, a PRS, as described above. In some aspects, the RIS may receive,from a UE, an SRS.

As further shown in FIG. 11 , process 1100 may include reflecting thePRS or SRS according to the configuration information (block 1130). Forexample, the RIS may reflect a PRS to a target UE according to theconfiguration information, as described above. In some aspects, the RISmay reflect a SRS to a target BS according to the configurationinformation, as described above.

Process 1100 may include additional implementations, such as any singleimplementation or any combination of implementations described belowand/or in connection with one or more other processes describedelsewhere herein.

In a first implementation, reflecting the PRS or SRS according to theconfiguration information comprises reflecting the PRS or SRS in aspecified direction.

In a second implementation, alone or in combination with the firstimplementation, reflecting the PRS or SRS in the specified directioncomprises reflecting a PRS towards a target UE, or reflecting a SRStowards a target BS.

In a third implementation, alone or in combination with one or more ofthe first and second implementations, reflecting the PRS or SRSaccording to the configuration information comprises reflecting the PRSor SRS as a beam of a specified beam width.

In a fourth implementation, alone or in combination with one or more ofthe first through third implementations, reflecting the PRS or SRS as abeam of a specified beam width comprises reflecting the PRS or SRS as abeam that is wider than, the same width as, or narrow than the PR PRS orSRS S being reflected.

In a fifth implementation, alone or in combination with one or more ofthe first through fourth implementations, the configuration informationis received from the BS.

Although FIG. 11 shows example blocks of process 1100, in someimplementations, process 1100 may include additional blocks, fewerblocks, different blocks, or differently arranged blocks than thosedepicted in FIG. 11 . Additionally, or alternatively, two or more of theblocks of process 1100 may be performed in parallel.

In the detailed description above it can be seen that different featuresare grouped together in examples. This manner of disclosure should notbe understood as an intention that the example clauses have morefeatures than are explicitly mentioned in each clause. Rather, thevarious aspects of the disclosure may include fewer than all features ofan individual example clause disclosed. Therefore, the following clausesshould hereby be deemed to be incorporated in the description, whereineach clause by itself can stand as a separate example. Although eachdependent clause can refer in the clauses to a specific combination withone of the other clauses, the aspect(s) of that dependent clause are notlimited to the specific combination. It will be appreciated that otherexample clauses can also include a combination of the dependent clauseaspect(s) with the subject matter of any other dependent clause orindependent clause or a combination of any feature with other dependentand independent clauses. The various aspects disclosed herein expresslyinclude these combinations, unless it is explicitly expressed or can bereadily inferred that a specific combination is not intended (e.g.,contradictory aspects, such as defining an element as both an electricalinsulator and an electrical conductor). Furthermore, it is also intendedthat aspects of a clause can be included in any other independentclause, even if the clause is not directly dependent on the independentclause.

Implementation examples are described in the following numbered clauses:

Clause 1. A method of wireless communication performed by a basestation, the method comprising: transmitting, to a user equipment (UE),a first positioning reference signal (PRS); transmitting, to areconfigurable intelligent surface (RIS) configured to reflect areceived signal to the UE, a second PRS; and receiving, from the UE, adownlink reference signal time difference (RSTD) measurement for thefirst PRS and the second PRS.

Clause 2. The method of clause 1, further comprising calculating anestimated position of the UE based on the RSTD measurements.

Clause 3. The method of any of clauses 1 to 2, further comprisingreceiving, from the UE, an estimated position of the UE.

Clause 4. The method of any of clauses 1 to 3, further comprising, priorto transmitting the second PRS, configuring the RIS to reflect areceived signal to the UE.

Clause 5. The method of clause 4, further comprising, prior totransmitting the first PRS, configuring the RIS to not reflect areceived signal to the UE.

Clause 6. The method of any of clauses 1 to 5, further comprising, priorto receiving the RSTD measurements, indicating, to the UE, atransmission time offset between the first PRS and the second PRS.

Clause 7. The method of clause 6, wherein indicating a transmission timeoffset between the first PRS and the second PRS comprises providing thetransmission time offset via explicit signaling, indicating thetransmission time offset based on a PRS mapping, or combinationsthereof.

Clause 8. The method of any of clauses 1 to 7, wherein receiving thedownlink reference signal time difference (RSTD) measurement for thefirst PRS and the second PRS comprises receiving a receive time, a timeof arrival, or combinations thereof for the first PRS and the secondPRS.

Clause 9. A method of wireless communication performed by a userequipment (UE), the method comprising: receiving, from a base station(BS), a first positioning reference signal (PRS); receiving, from areconfigurable intelligent surface (RIS) configured to reflect areceived signal to the UE, a second PRS; and transmitting, to the BS, adownlink reference signal time difference (RSTD) measurement for thefirst PRS and the second PRS.

Clause 10. The method of clause 9, further comprising: determining atransmission time offset between the first PRS and the second PRS;calculating an estimated position of the UE based on the RSTDmeasurements and the transmission time offset between the first PRS andthe second PRS; and transmitting, to the BS, the estimated position ofthe UE.

Clause 11. The method of clause 10, wherein determining the transmissiontime offset between the first PRS and the second PRS comprises receivingthe transmission time offset via explicit signaling, determining thetransmission time offset based on a PRS mapping, or combinationsthereof.

Clause 12. The method of any of clauses 9 to 11, wherein transmittingthe downlink reference signal time difference (RSTD) measurement for thefirst PRS and the second PRS comprises transmitting a receive time, atime of arrival, or combinations thereof for the first PRS and thesecond PRS.

Clause 13. A method of wireless communication performed by areconfigurable intelligent surface (RIS), the method comprising:receiving configuration information for configuring the RIS to reflect areceived signal; receiving a positioning reference signal (PRS) or asounding reference signal (SRS); and reflecting the PRS or SRS accordingto the configuration information.

Clause 14. The method of clause 13, wherein reflecting the PRS or SRSaccording to the configuration information comprises reflecting the PRSor SRS in a specified direction.

Clause 15. The method of clause 14, wherein reflecting the PRS or SRS inthe specified direction comprises reflecting a PRS towards a target userequipment (UE).

Clause 16. The method of any of clauses 14 to 15, wherein reflecting thePRS or SRS in the specified direction comprises reflecting a SRS towardsa target base station (BS).

Clause 17. The method of any of clauses 13 to 16, wherein reflecting thePRS or SRS according to the configuration information comprisesreflecting the PRS or SRS as a beam of a specified beam width.

Clause 18. The method of clause 17, wherein reflecting the PRS or SRS asa beam of a specified beam width comprises reflecting the PRS or SRS asa beam that is wider than, a same width as, or narrower than, the PRS orSRS being reflected.

Clause 19. The method of any of clauses 13 to 18, wherein theconfiguration information is received from a base station (BS).

Clause 20. A base station (BS), comprising: one or more memories; one ormore processors, communicatively coupled to the one or more memories,configured to: cause the BS to transmit, to a user equipment (UE), afirst positioning reference signal (PRS); cause the BS to transmit, to areconfigurable intelligent surface (RIS) configured to reflect areceived signal to the UE, a second PRS; and receive, from the UE, adownlink reference signal time difference (RSTD) measurement for thefirst PRS and the second PRS.

Clause 21. The BS of clause 20, wherein the one or more processors arefurther configured to calculate an estimated position of the UE based onthe RSTD measurements.

Clause 22. The BS of any of clauses 20 to 21, wherein the one or moreprocessors are further configured to receive, from the UE, an estimatedposition of the UE.

Clause 23. The BS of any of clauses 20 to 22, wherein the one or moreprocessors are further configured to, prior to transmitting the secondPRS, configure the RIS to reflect a received signal to the UE.

Clause 24. The BS of clause 23, wherein the one or more processors arefurther configured to, prior to transmitting the first PRS, configurethe RIS to not reflect a received signal to the UE.

Clause 25. The BS of any of clauses 20 to 24, wherein the one or moreprocessors are further configured to, prior to receiving the RSTDmeasurements, indicate, to the UE, a transmission time offset betweenthe first PRS and the second PRS.

Clause 26. The BS of clause 25, wherein the one or more processors, whenindicating a transmission time offset between the first PRS and thesecond PRS, are configured to provide the transmission time offset viaexplicit signaling, indicating the transmission time offset based on aPRS mapping, or combinations thereof.

Clause 27. The BS of any of clauses 20 to 26, wherein the one or moreprocessors, when receiving the downlink reference signal time difference(RSTD) measurement for the first PRS and the second PRS, are configuredto receive a receive time, a time of arrival, or combinations thereoffor the first PRS and the second PRS.

Clause 28. A user equipment (UE), comprising: one or more memories; oneor more processors, communicatively coupled to the one or more memories,configured to: receive, from a base station (BS), a first positioningreference signal (PRS); receive, from a reconfigurable intelligentsurface (RIS) configured to reflect a received signal to the UE, asecond PRS; and cause the UE to transmit, to the BS, a downlinkreference signal time difference (RSTD) measurement for the first PRSand the second PRS.

Clause 29. The UE of clause 28, wherein the one or more processors arefurther configured to: determine a transmission time offset between thefirst PRS and the second PRS; calculate an estimated position of the UEbased on the RSTD measurements and the transmission time offset betweenthe first PRS and the second PRS; and transmit, to the BS, the estimatedposition of the UE.

Clause 30. The UE of clause 29, wherein the one or more processors, whendetermining the transmission time offset between the first PRS and thesecond PRS, are configured to receive the transmission time offset viaexplicit signaling, to determine the transmission time offset based on aPRS mapping, or combinations thereof.

Clause 31. The UE of any of clauses 28 to 30, wherein the one or moreprocessors, when transmitting the downlink reference signal timedifference (RSTD) measurement for the first PRS and the second PRS, areconfigured to transmit a receive time, a time of arrival, orcombinations thereof for the first PRS and the second PRS.

Clause 32. A reconfigurable intelligent surface (RIS), comprising: oneor more memories; one or more processors, communicatively coupled to theone or more memories, configured to: receive configuration informationfor configuring the RIS to reflect a received signal; receive apositioning reference signal (PRS) or a sounding reference signal (SRS);and cause the RIS to reflect the PRS or SRS according to theconfiguration information.

Clause 33. The RIS of clause 32, wherein the one or more processors,when reflecting the PRS or SRS according to the configurationinformation, are configured to reflect the PRS or SRS in a specifieddirection.

Clause 34. The RIS of clause 33, wherein the one or more processors,when reflecting the PRS or SRS in the specified direction, areconfigured to reflect a PRS towards a target user equipment (UE).

Clause 35. The RIS of any of clauses 33 to 34, wherein the one or moreprocessors, when reflecting the PRS or SRS in the specified direction,are configured to reflect a SRS towards a target base station (BS).

Clause 36. The RIS of any of clauses 32 to 35, wherein the one or moreprocessors, when reflecting the PRS or SRS according to theconfiguration information, are configured to reflect the PRS or SRS as abeam of a specified beam width.

Clause 37. The RIS of clause 36, wherein the one or more processors,when reflecting the PRS or SRS as a beam of a specified beam width, areconfigured to reflect the PRS or SRS as a beam that is wider than, asame width as, or narrower than the PRS or SRS being reflected.

Clause 38. The RIS of any of clauses 32 to 37, wherein the configurationinformation is received from a base station (BS).

Clause 39. A base station (BS), comprising: means for transmitting, to auser equipment (UE), a first positioning reference signal (PRS); meansfor transmitting, to a reconfigurable intelligent surface (RIS)configured to reflect a received signal to the UE, a second PRS; andmeans for receiving, from the UE, a downlink reference signal timedifference (RSTD) measurement for the first PRS and the second PRS.

Clause 40. A user equipment (UE), comprising: means for receiving, froma base station (BS), a first positioning reference signal (PRS); meansfor receiving, from a reconfigurable intelligent surface (RIS)configured to reflect a received signal to the UE, a second PRS; andmeans for transmitting, to the BS, a downlink reference signal timedifference (RSTD) measurement for the first PRS and the second PRS.

Clause 41. A reconfigurable intelligent surface (RIS), comprising: meansfor receiving configuration information for configuring the RIS toreflect a received signal; means for receiving a positioning referencesignal (PRS) or a sounding reference signal (SRS); and means forreflecting the PRS or SRS according to the configuration information.

Clause 42. A non-transitory computer-readable medium storing a set ofinstructions, the set of instructions comprising one or moreinstructions that, when executed by one or more processors of a basestation (BS), cause the base station to: transmit, to a user equipment(UE), a first positioning reference signal (PRS); transmit, to areconfigurable intelligent surface (RIS) configured to reflect areceived signal to the UE, a second PRS; and receive, from the UE, adownlink reference signal time difference (RSTD) measurement for thefirst PRS and the second PRS.

Clause 43. A non-transitory computer-readable medium storing a set ofinstructions, the set of instructions comprising one or moreinstructions that, when executed by one or more processors of a userequipment (UE), cause the UE to: receive, from a base station (BS), afirst positioning reference signal (PRS); receive, from a reconfigurableintelligent surface (RIS) configured to reflect a received signal to theUE, a second PRS; and transmit, to the BS, a downlink reference signaltime difference (RSTD) measurement for the first PRS and the second PRS.

Clause 44. A non-transitory computer-readable medium storing a set ofinstructions, the set of instructions comprising one or moreinstructions that, when executed by one or more processors of areconfigurable intelligent surface (RIS), cause the RIS to: receiveconfiguration information for configuring the RIS to reflect a receivedsignal; receive a positioning reference signal (PRS) or a soundingreference signal (SRS); and reflect the PRS or SRS according to theconfiguration information.

Clause 39. An apparatus comprising a memory, a transceiver, and aprocessor communicatively coupled to the memory and the transceiver, thememory, the transceiver, and the processor configured to perform amethod according to any of clauses 1 to 19.

Clause 40. An apparatus comprising means for performing a methodaccording to any of clauses 1 to 19.

Clause 41. A non-transitory computer-readable medium storingcomputer-executable instructions, the computer-executable comprising atleast one instruction for causing a computer or processor to perform amethod according to any of clauses 1 to 19.

Additional aspects include at least the following:

In an aspect, a method of wireless communication performed by a basestation includes transmitting, to a user equipment (UE), a firstpositioning reference signal (PRS), transmitting, to a reconfigurableintelligent surface (RIS) configured to reflect a received signal to theUE, a second PRS, and receiving, from the UE, a downlink referencesignal time difference (RSTD) measurement for the first PRS and thesecond PRS.

In some aspects, the method includes calculating an estimated positionof the UE based on the RSTD measurements.

In some aspects, the method includes receiving, from the UE, anestimated position of the UE.

In some aspects, the method includes prior to transmitting the secondPRS, configuring the RIS to reflect a received signal to the UE.

In some aspects, the method includes prior to transmitting the firstPRS, configuring the RIS to not reflect a received signal to the UE.

In some aspects, the method includes prior to receiving the RSTDmeasurements, indicating, to the UE, a transmission time offset betweenthe first PRS and the second PRS.

In some aspects, indicating a transmission time offset between the firstPRS and the second PRS comprises providing the transmission time offsetvia explicit signaling, indicating the transmission time offset based ona PRS mapping, or combinations thereof.

In some aspects, receiving the downlink reference signal time difference(RSTD) measurement for the first PRS and the second PRS comprisesreceiving a receive time, a time of arrival, or combinations thereof forthe first PRS and the second PRS.

In an aspect, a method of wireless communication performed by a userequipment (UE) includes receiving, from a base station (BS), a firstpositioning reference signal (PRS), receiving, from a reconfigurableintelligent surface (RIS) configured to reflect a received signal to theUE, a second PRS, and transmitting, to the BS, a downlink referencesignal time difference (RSTD) measurement for the first PRS and thesecond PRS.

In some aspects, the method includes determining a transmission timeoffset between the first PRS and the second PRS, calculating anestimated position of the UE based on the RSTD measurements and thetransmission time offset between the first PRS and the second PRS, andtransmitting, to the BS, the estimated position of the UE.

In some aspects, determining the transmission time offset between thefirst PRS and the second PRS comprises receiving the transmission timeoffset via explicit signaling, determining the transmission time offsetbased on a PRS mapping, or combinations thereof.

In some aspects, transmitting the downlink reference signal timedifference (RSTD) measurement for the first PRS and the second PRScomprises transmitting a receive time, a time of arrival, orcombinations thereof for the first PRS and the second PRS.

In an aspect, a method of wireless communication performed by areconfigurable intelligent surface (RIS) includes receivingconfiguration information for configuring the RIS to reflect a receivedsignal, receiving a positioning reference signal (PRS) or a soundingreference signal (SRS), and reflecting the PRS or SRS according to theconfiguration information.

In some aspects, reflecting the PRS or SRS according to theconfiguration information comprises reflecting the PRS or SRS in aspecified direction.

In some aspects, reflecting the PRS or SRS in the specified directioncomprises reflecting a PRS towards a target user equipment (UE).

In some aspects, reflecting the PRS or SRS in the specified directioncomprises reflecting a SRS towards a target base station (BS).

In some aspects, reflecting the PRS or SRS according to theconfiguration information comprises reflecting the PRS or SRS as a beamof a specified beam width.

In some aspects, reflecting the PRS or SRS as a beam of a specified beamwidth comprises reflecting the PRS or SRS as a beam that is wider than,a same width as, or narrower than, the PRS or SRS being reflected.

In some aspects, the configuration information is received from a basestation (BS).

In an aspect, a base station (BS) includes one or more memories, one ormore processors, communicatively coupled to the one or more memories,configured to: cause the BS to transmit, to a user equipment (UE), afirst positioning reference signal (PRS), cause the BS to transmit, to areconfigurable intelligent surface (RIS) configured to reflect areceived signal to the UE, a second PRS, and receive, from the UE, adownlink reference signal time difference (RSTD) measurement for thefirst PRS and the second PRS.

In some aspects, the one or more processors are further configured tocalculate an estimated position of the UE based on the RSTDmeasurements.

In some aspects, the one or more processors are further configured toreceive, from the UE, an estimated position of the UE.

In some aspects, the one or more processors are further configured to,prior to transmitting the second PRS, configure the RIS to reflect areceived signal to the UE.

In some aspects, the one or more processors are further configured to,prior to transmitting the first PRS, configure the RIS to not reflect areceived signal to the UE.

In some aspects, the one or more processors are further configured to,prior to receiving the RSTD measurements, indicate, to the UE, atransmission time offset between the first PRS and the second PRS.

In some aspects, the one or more processors, when indicating atransmission time offset between the first PRS and the second PRS, areconfigured to provide the transmission time offset via explicitsignaling, indicating the transmission time offset based on a PRSmapping, or combinations thereof.

In some aspects, the one or more processors, when receiving the downlinkreference signal time difference (RSTD) measurement for the first PRSand the second PRS, are configured to receive a receive time, a time ofarrival, or combinations thereof for the first PRS and the second PRS.

In an aspect, a user equipment (UE) includes one or more memories, oneor more processors, communicatively coupled to the one or more memories,configured to: receive, from a base station (BS), a first positioningreference signal (PRS), receive, from a reconfigurable intelligentsurface (RIS) configured to reflect a received signal to the UE, asecond PRS, and cause the UE to transmit, to the BS, a downlinkreference signal time difference (RSTD) measurement for the first PRSand the second PRS.

In some aspects, the one or more processors are further configured to:determine a transmission time offset between the first PRS and thesecond PRS, calculate an estimated position of the UE based on the RSTDmeasurements and the transmission time offset between the first PRS andthe second PRS, and transmit, to the BS, the estimated position of theUE.

In some aspects, the one or more processors, when determining thetransmission time offset between the first PRS and the second PRS, areconfigured to receive the transmission time offset via explicitsignaling, to determine the transmission time offset based on a PRSmapping, or combinations thereof.

In some aspects, the one or more processors, when transmitting thedownlink reference signal time difference (RSTD) measurement for thefirst PRS and the second PRS, are configured to transmit a receive time,a time of arrival, or combinations thereof for the first PRS and thesecond PRS.

In an aspect, a reconfigurable intelligent surface (RIS) includes one ormore memories, one or more processors, communicatively coupled to theone or more memories, configured to: receive configuration informationfor configuring the RIS to reflect a received signal, receive apositioning reference signal (PRS) or a sounding reference signal (SRS),and cause the RIS to reflect the PRS or SRS according to theconfiguration information.

In some aspects, the one or more processors, when reflecting the PRS orSRS according to the configuration information, are configured toreflect the PRS or SRS in a specified direction.

In some aspects, the one or more processors, when reflecting the PRS orSRS in the specified direction, are configured to reflect a PRS towardsa target user equipment (UE).

In some aspects, the one or more processors, when reflecting the PRS orSRS in the specified direction, are configured to reflect a SRS towardsa target base station (BS).

In some aspects, the one or more processors, when reflecting the PRS orSRS according to the configuration information, are configured toreflect the PRS or SRS as a beam of a specified beam width.

In some aspects, the one or more processors, when reflecting the PRS orSRS as a beam of a specified beam width, are configured to reflect thePRS or SRS as a beam that is wider than, a same width as, or narrowerthan the PRS or SRS being reflected.

In some aspects, the configuration information is received from a basestation (BS).

In an aspect, a base station (BS) includes means for transmitting, to auser equipment (UE), a first positioning reference signal (PRS), meansfor transmitting, to a reconfigurable intelligent surface (RIS)configured to reflect a received signal to the UE, a second PRS, andmeans for receiving, from the UE, a downlink reference signal timedifference (RSTD) measurement for the first PRS and the second PRS.

In an aspect, a user equipment (UE) includes means for receiving, from abase station (BS), a first positioning reference signal (PRS), means forreceiving, from a reconfigurable intelligent surface (RIS) configured toreflect a received signal to the UE, a second PRS, and means fortransmitting, to the BS, a downlink reference signal time difference(RSTD) measurement for the first PRS and the second PRS.

In an aspect, a reconfigurable intelligent surface (RIS) includes meansfor receiving configuration information for configuring the RIS toreflect a received signal, means for receiving a positioning referencesignal (PRS) or a sounding reference signal (SRS), and means forreflecting the PRS or SRS according to the configuration information.

In an aspect, a non-transitory computer-readable medium storing a set ofinstructions, the set of instructions comprising one or moreinstructions that, when executed by one or more processors of a basestation (BS), cause the base station to: transmit, to a user equipment(UE), a first positioning reference signal (PRS), transmit, to areconfigurable intelligent surface (RIS) configured to reflect areceived signal to the UE, a second PRS, and receive, from the UE, adownlink reference signal time difference (RSTD) measurement for thefirst PRS and the second PRS.

In an aspect, a non-transitory computer-readable medium storing a set ofinstructions, the set of instructions comprising one or moreinstructions that, when executed by one or more processors of a userequipment (UE), cause the UE to: receive, from a base station (BS), afirst positioning reference signal (PRS), receive, from a reconfigurableintelligent surface (RIS) configured to reflect a received signal to theUE, a second PRS, and transmit, to the BS, a downlink reference signaltime difference (RSTD) measurement for the first PRS and the second PRS.

In an aspect, a non-transitory computer-readable medium storing a set ofinstructions, the set of instructions comprising one or moreinstructions that, when executed by one or more processors of areconfigurable intelligent surface (RIS), cause the RIS to: receiveconfiguration information for configuring the RIS to reflect a receivedsignal, receive a positioning reference signal (PRS) or a soundingreference signal (SRS), and reflect the PRS or SRS according to theconfiguration information.

Those of skill in the art will appreciate that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or any combination thereof.

Further, those of skill in the art will appreciate that the variousillustrative logical blocks, modules, circuits, and algorithm stepsdescribed in connection with the aspects disclosed herein may beimplemented as electronic hardware, computer software, or combinationsof both. To clearly illustrate this interchangeability of hardware andsoftware, various illustrative components, blocks, modules, circuits,and steps have been described above generally in terms of theirfunctionality. Whether such functionality is implemented as hardware orsoftware depends upon the particular application and design constraintsimposed on the overall system. Skilled artisans may implement thedescribed functionality in varying ways for each particular application,but such implementation decisions should not be interpreted as causing adeparture from the scope of the present disclosure.

The various illustrative logical blocks, modules, and circuits describedin connection with the aspects disclosed herein may be implemented orperformed with a general purpose processor, a DSP, an ASIC, an FPGA, orother programmable logic device, discrete gate or transistor logic,discrete hardware components, or any combination thereof designed toperform the functions described herein. A general purpose processor maybe a microprocessor, but in the alternative, the processor may be anyconventional processor, controller, microcontroller, or state machine. Aprocessor may also be implemented as a combination of computing devices,e.g., a combination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration.

The methods, sequences and/or algorithms described in connection withthe aspects disclosed herein may be embodied directly in hardware, in asoftware module executed by a processor, or in a combination of the two.A software module may reside in random access memory (RAM), flashmemory, read-only memory (ROM), erasable programmable ROM (EPROM),electrically erasable programmable ROM (EEPROM), registers, hard disk, aremovable disk, a CD-ROM, or any other form of storage medium known inthe art. An example storage medium is coupled to the processor such thatthe processor can read information from, and write information to, thestorage medium. In the alternative, the storage medium may be integralto the processor. The processor and the storage medium may reside in anASIC. The ASIC may reside in a user terminal (e.g., UE). In thealternative, the processor and the storage medium may reside as discretecomponents in a user terminal.

In one or more example aspects, the functions described may beimplemented in hardware, software, firmware, or any combination thereof.If implemented in software, the functions may be stored on ortransmitted over as one or more instructions or code on acomputer-readable medium. Computer-readable media includes both computerstorage media and communication media including any medium thatfacilitates transfer of a computer program from one place to another. Astorage media may be any available media that can be accessed by acomputer. By way of example, and not limitation, such computer-readablemedia can comprise RAM, ROM, EEPROM, CD-ROM or other optical diskstorage, magnetic disk storage or other magnetic storage devices, or anyother medium that can be used to carry or store desired program code inthe form of instructions or data structures and that can be accessed bya computer. Also, any connection is properly termed a computer-readablemedium. For example, if the software is transmitted from a website,server, or other remote source using a coaxial cable, fiber optic cable,twisted pair, digital subscriber line (DSL), or wireless technologiessuch as infrared, radio, and microwave, then the coaxial cable, fiberoptic cable, twisted pair, DSL, or wireless technologies such asinfrared, radio, and microwave are included in the definition of medium.Disk and disc, as used herein, includes compact disc (CD), laser disc,optical disc, digital versatile disc (DVD), floppy disk and Blu-ray discwhere disks usually reproduce data magnetically, while discs reproducedata optically with lasers. Combinations of the above should also beincluded within the scope of computer-readable media.

While the foregoing disclosure shows illustrative aspects of thedisclosure, it should be noted that various changes and modificationscould be made herein without departing from the scope of the disclosureas defined by the appended claims. The functions, steps and/or actionsof the method claims in accordance with the aspects of the disclosuredescribed herein need not be performed in any particular order.Furthermore, although elements of the disclosure may be described orclaimed in the singular, the plural is contemplated unless limitation tothe singular is explicitly stated.

What is claimed is:
 1. A method of wireless communication performed by abase station, the method comprising: transmitting, to a user equipment(UE), a first positioning reference signal (PRS); transmitting, to areconfigurable intelligent surface (RIS) configured to reflect areceived signal to the UE, a second PRS; and receiving, from the UE, adownlink reference signal time difference (RSTD) measurement for thefirst PRS and the second PRS.
 2. The method of claim 1, furthercomprising calculating an estimated position of the UE based on the RSTDmeasurements.
 3. The method of claim 1, further comprising receiving,from the UE, an estimated position of the UE.
 4. The method of claim 1,further comprising, prior to transmitting the second PRS, configuringthe RIS to reflect a received signal to the UE.
 5. The method of claim4, further comprising, prior to transmitting the first PRS, configuringthe RIS to not reflect a received signal to the UE.
 6. The method ofclaim 1, further comprising, prior to receiving the RSTD measurements,indicating, to the UE, a transmission time offset between the first PRSand the second PRS.
 7. The method of claim 6, wherein indicating atransmission time offset between the first PRS and the second PRScomprises providing the transmission time offset via explicit signaling,indicating the transmission time offset based on a PRS mapping, orcombinations thereof.
 8. The method of claim 1, wherein receiving thedownlink reference signal time difference (RSTD) measurement for thefirst PRS and the second PRS comprises receiving a receive time, a timeof arrival, or combinations thereof for the first PRS and the secondPRS.
 9. A method of wireless communication performed by a user equipment(UE), the method comprising: receiving, from a base station (BS), afirst positioning reference signal (PRS); receiving, from areconfigurable intelligent surface (RIS) configured to reflect areceived signal to the UE, a second PRS; and transmitting, to the BS, adownlink reference signal time difference (RSTD) measurement for thefirst PRS and the second PRS.
 10. The method of claim 9, furthercomprising: determining a transmission time offset between the first PRSand the second PRS; calculating an estimated position of the UE based onthe RSTD measurements and the transmission time offset between the firstPRS and the second PRS; and transmitting, to the BS, the estimatedposition of the UE.
 11. The method of claim 10, wherein determining thetransmission time offset between the first PRS and the second PRScomprises receiving the transmission time offset via explicit signaling,determining the transmission time offset based on a PRS mapping, orcombinations thereof.
 12. The method of claim 9, wherein transmittingthe downlink reference signal time difference (RSTD) measurement for thefirst PRS and the second PRS comprises transmitting a receive time, atime of arrival, or combinations thereof for the first PRS and thesecond PRS.
 13. A method of wireless communication performed by areconfigurable intelligent surface (RIS), the method comprising:receiving configuration information for configuring the RIS to reflect areceived signal; receiving a positioning reference signal (PRS) or asounding reference signal (SRS); and reflecting the PRS or SRS accordingto the configuration information.
 14. The method of claim 13, whereinreflecting the PRS or SRS according to the configuration informationcomprises reflecting the PRS or SRS in a specified direction.
 15. Themethod of claim 14, wherein reflecting the PRS or SRS in the specifieddirection comprises reflecting a PRS towards a target user equipment(UE).
 16. The method of claim 14, wherein reflecting the PRS or SRS inthe specified direction comprises reflecting a SRS towards a target basestation (BS).
 17. The method of claim 13, wherein reflecting the PRS orSRS according to the configuration information comprises reflecting thePRS or SRS as a beam of a specified beam width.
 18. The method of claim17, wherein reflecting the PRS or SRS as a beam of a specified beamwidth comprises reflecting the PRS or SRS as a beam that is wider than,a same width as, or narrower than, the PRS or SRS being reflected. 19.The method of claim 13, wherein the configuration information isreceived from a base station (BS).
 20. A base station (BS), comprising:one or more memories; one or more processors, communicatively coupled tothe one or more memories, configured to: cause the BS to transmit, to auser equipment (UE), a first positioning reference signal (PRS); causethe BS to transmit, to a reconfigurable intelligent surface (RIS)configured to reflect a received signal to the UE, a second PRS; andreceive, from the UE, a downlink reference signal time difference (RSTD)measurement for the first PRS and the second PRS.
 21. The BS of claim20, wherein the one or more processors are further configured tocalculate an estimated position of the UE based on the RSTDmeasurements.
 22. The BS of claim 20, wherein the one or more processorsare further configured to receive, from the UE, an estimated position ofthe UE.
 23. The BS of claim 20, wherein the one or more processors arefurther configured to, prior to transmitting the second PRS, configurethe RIS to reflect a received signal to the UE.
 24. The BS of claim 23,wherein the one or more processors are further configured to, prior totransmitting the first PRS, configure the RIS to not reflect a receivedsignal to the UE.
 25. The BS of claim 20, wherein the one or moreprocessors are further configured to, prior to receiving the RSTDmeasurements, indicate, to the UE, a transmission time offset betweenthe first PRS and the second PRS.
 26. The BS of claim 25, wherein theone or more processors, when indicating a transmission time offsetbetween the first PRS and the second PRS, are configured to provide thetransmission time offset via explicit signaling, indicating thetransmission time offset based on a PRS mapping, or combinationsthereof.
 27. The BS of claim 20, wherein the one or more processors,when receiving the downlink reference signal time difference (RSTD)measurement for the first PRS and the second PRS, are configured toreceive a receive time, a time of arrival, or combinations thereof forthe first PRS and the second PRS.
 28. A user equipment (UE), comprising:one or more memories; one or more processors, communicatively coupled tothe one or more memories, configured to: receive, from a base station(BS), a first positioning reference signal (PRS); receive, from areconfigurable intelligent surface (RIS) configured to reflect areceived signal to the UE, a second PRS; and cause the UE to transmit,to the BS, a downlink reference signal time difference (RSTD)measurement for the first PRS and the second PRS.
 29. The UE of claim28, wherein the one or more processors are further configured to:determine a transmission time offset between the first PRS and thesecond PRS; calculate an estimated position of the UE based on the RSTDmeasurements and the transmission time offset between the first PRS andthe second PRS; and transmit, to the BS, the estimated position of theUE.
 30. The UE of claim 29, wherein the one or more processors, whendetermining the transmission time offset between the first PRS and thesecond PRS, are configured to receive the transmission time offset viaexplicit signaling, to determine the transmission time offset based on aPRS mapping, or combinations thereof.
 31. The UE of claim 28, whereinthe one or more processors, when transmitting the downlink referencesignal time difference (RSTD) measurement for the first PRS and thesecond PRS, are configured to transmit a receive time, a time ofarrival, or combinations thereof for the first PRS and the second PRS.32. A reconfigurable intelligent surface (RIS), comprising: one or morememories; one or more processors, communicatively coupled to the one ormore memories, configured to: receive configuration information forconfiguring the RIS to reflect a received signal; receive a positioningreference signal (PRS) or a sounding reference signal (SRS); and causethe RIS to reflect the PRS or SRS according to the configurationinformation.
 33. The RIS of claim 32, wherein the one or moreprocessors, when reflecting the PRS or SRS according to theconfiguration information, are configured to reflect the PRS or SRS in aspecified direction.
 34. The RIS of claim 33, wherein the one or moreprocessors, when reflecting the PRS or SRS in the specified direction,are configured to reflect a PRS towards a target user equipment (UE).35. The RIS of claim 33, wherein the one or more processors, whenreflecting the PRS or SRS in the specified direction, are configured toreflect a SRS towards a target base station (BS).
 36. The RIS of claim32, wherein the one or more processors, when reflecting the PRS or SRSaccording to the configuration information, are configured to reflectthe PRS or SRS as a beam of a specified beam width.
 37. The RIS of claim36, wherein the one or more processors, when reflecting the PRS or SRSas a beam of a specified beam width, are configured to reflect the PRSor SRS as a beam that is wider than, a same width as, or narrower thanthe PRS or SRS being reflected.
 38. The RIS of claim 32, wherein theconfiguration information is received from a base station (BS).